Home » MODERN WORLD HISTORY » 1900-PRESENT

Conflict has taken place in every year of the 20th Century; the world was free from the violence caused by war for only very short periods of time. It has been estimated that 187 million people died as a result of war from 1900 to the present. The actual number is likely far higher.

The following list highlights just some of the conflicts that have impacted the lives of people from the United Kingdom, the British Empire, and the Commonwealth since 1900. The Imperial War Museum (IWM) records and preserves stories from many of these conflicts in its collections. 

Discover more about each conflict by searching IWM’s extensive collections.

You will find that each conflict is described with a set of dates, which implies a defined ‘beginning and end’. While this is useful to help with classification, it is important to note that the causes and consequences of individual wars or conflicts extend far beyond these narrow ranges. Frequently, there are wider issues that connect many of them together; exploring and documenting these links through our collections is an ongoing process.

Essential Events Between 1900 and 1945

Find out how two world wars and other major historical developments from the Spanish-American War to World War II reshaped global affairs in the first half of the twentieth century.

World History Timeline: 1898–1945

1898

Spanish-American War Signals Growing U.S. Ambition on World Stage

On February 15th, 1898, the  USS Maine exploded in Cuban waters. 266 Americans on board the vessel were killed, leaving the nation reeling and eager to find the perpetrator. Following the explosion, sensational news reports blamed Spain. After riling up public support, the United States declared war on Spain, entering Cuba’s war for independence from its Spanish colonizers. But what then-U.S. Secretary of State John Hay, referred to as a “splendid little war” was more than just a major power struggle over interests in the Americas.  Rather, the conflict clearly signaled the United States’ growing ambitions on the world stage and, in this case, closer to home. Nearly three hundred thousand Americans, including Theodore Roosevelt’s Rough Riders, answered President William McKinley’s call for troops. After months of fighting, Cuba emerged with its independence, and the United States emerged with much of Spain’s colonial empire in the Caribbean and Pacific. Following the Spanish-American War, the U.S. claimed control of Guam, the Philippines, and Puerto Rico. Additionally, the Platt Amendment, which the United States insisted be part of the Cuban constitution, designated Guantanamo Bay as a permanent U.S. military base. A country whose sovereignty once failed to span its own mainland now controlled territories across the globe.

1905

Japan Gains International Reputation With Victory in Russo-Japanese War

The breakout of the Russo-Japanese War in 1904 capped a decades-long tussle between Japan and Russia over the resource-rich region of Manchuria. Japan emerged victorious, proving its capacity to trump Western military might—a rarity in the nineteenth century. This milestone helped cement Japan’s reputation as a growing military and colonial power, one to be treated as an equal—diplomatically—by Western powers. The failed military campaign weakened the prestige of czarist Russia, dampening imperial ambitions in East Asia and nearly leading to revolution at home. By the conflict’s close, Japan controlled much of southern Manchuria and the region’s valuable mining and railroad interests; by 1910, the island nation had fulfilled further imperial ambitions by annexing Korea.

1906

Launch of HMS Dreadnought Sparks Arms Race

The late nineteenth and early twentieth centuries were periods of rapid technological innovation. The automobile, radio, and television—invented in 1886, 1901, and 1927 respectively—would all go on to change the course of history. But it was the launch of the British warship HMS Dreadnought that sparked the first arms race of the twentieth century. The ship, a feat of naval engineering, featured twelve-inch guns, submerged torpedo tubes, and steam turbine engines, which had never been brought together before. The following arms race on land produced long-range weapons, chemical gas, and difficult-to-reverse military mobilizations. This frenzied militarization among the world’s most powerful countries contributed to the inevitability of World War I.

Jun 28, 1914

Assassination of Archduke Franz Ferdinand Ignites World War I

On June 28, 1914, Archduke Franz Ferdinand, heir to the throne of Austria-Hungary, was assassinated. The murder of Franz Ferdinand caused tensions to boil over in Europe, leading to the start of World War I. But why did the assassination of one man cause the whole world to dive into conflict? The short version: it’s complicated. The longer version requires looking at the long-term forces that led to mutual hostility and suspicion among European powers. These forces include fervent nationalism, imperial competition for new markets, an arms race, mobilization plans, and values such as militarism. Additionally, alliance systems, meant to act as a deterrent to conflict, dragged their members into war. These forces produced a conflict that would turn what most thought would be a quick “home by the holidays” skirmish into a deadly four-year military engagement. The so-called “Great War” was a continent-spanning conflict between the Central Powers (Austria-Hungary, Germany, and the Ottoman Empire) and the Allied Powers (Britain, France, Russia, and eventually Italy and the United States). Other countries such as China and Japan were also involved in the fighting. Ultimately, World War I killed approximately nine million soldiers, which at the time was the deadliest war in European history.

Aug 15, 1914

Panama Canal Transforms U.S. and Global Economy

After gold was discovered in California in 1848, Americans were desperate for a faster way to get from coast to coast. This desire only increased when Hawaii and the Philippines became U.S. territories; empire-building highlighted the need for a shortcut between the Atlantic and Pacific Oceans. To accommodate their imperial ambitions, the United States needed a route that would allow warships and commercial vessels to get from one U.S. coast to another without rounding South America. By encouraging and supporting Panama’s push for independence from Colombia, the United States ultimately succeeded in building the Panama Canal. The waterway officially opened to traffic in 1914. The United States could now sail far more easily and safely between its two shores. This man-made feat allowed the country to integrate its domestic economy and continue on its path toward becoming a global superpower. 

Apr 1, 1915 – May 31, 1915

Second Battle of Ypres Introduces World to Large-Scale Chemical Warfare

From the use of tanks and submarines to the widespread deployment of fighter pilots and new military uniforms with steel helmets, World War I was truly a conflict of military firsts. Sadly, this also marked the first time chemical weapons and machine guns were used on such a massive scale. Throughout the war, the machine gun resulted in massive casualties. Soldiers could shoot rapidly and continuously to great effect without even aiming at a specific target. During the Second Battle of Ypres, the German army opened thousands of cylinders of chlorine gas in the trenches along its defensive perimeter in Belgium. The results were immediate. A wall of gas killed more than six thousand Algerian and French soldiers and harmed thousands more. The war marked the first time in modern warfare that an army used weapons of mass destruction. This fateful milestone would be repeated during World War I and in future conflicts, inspiring international backlash and the ultimate emergence of the Chemical Weapons Convention in 1993. 

May 16, 1916

Sykes-Picot Agreement Leads to Ottoman Empire Break-Up

Anticipating a victory, two senior diplomats—Britain’s Sir Mark Sykes and France’s Francois Georges Picot—met in secret at the height of World War I to plan ahead for the changing world order. Sykes and Picot agreed to preemptively divide up the fallen Ottoman Empire into their respective spheres of influence. This territory included present-day Turkey and most of the Arab Middle East. When Bolshevik Russia leaked news of the meeting, outrage ensued due to Britain’s clear intention to withdraw its promised support for an independent Arab kingdom. Despite the leak, the terms of the Sykes-Picot Agreement, which eventually included Italy and Russia, were mostly codified by the Treaty of Sèvres. Both Britain and France went on to draw new borders that had less to do with the people living in those areas and more to do with imperial ambition. In fact, the victors of World War I had designs to fuel their empires: European access to oil and Mediterranean seaports held supremacy over respect for Middle Eastern sovereignty. 

January 1917

Zimmerman Telegram Helps to Push United States into World War I

Despite its growing global power, the United States sought to stay out of World War I. Its resolve was tested in 1915 when German submarines attacked a British ocean liner, the RMS Lusitania. The assault killed nearly 1,200 people, including over 100 Americans. In a bid to maintain American neutrality and respond to public condemnation, Germany agreed to cease its submarine activity against civilian shipping. However, in 1917, Britain intercepted a note sent by Germany to Mexico proposing a military alliance and promising to help Mexico reclaim lost territory from the Mexican-American War. The Zimmerman Telegram, coupled with  Germany’s decision to resume unrestricted submarine warfare in 1917, led a reluctant United States into the war. By July 1918, one million American troops had arrived in Europe to fight with the Allied forces; by November, Germany was fatally weakened and the war was over.

Nov 7, 1917

Bolshevik Revolution Leads to the birth of the Soviet Union

After sustaining territorial losses in the early twentieth century and devastating loss of life during World War I, the czarist regime in Russia was on the verge of collapse. In early 1917, protests led by working-class women, and joined by factory workers and deserted soldiers, escalated into a revolution. By the end of that year, revolutionaries overthrew Tsar Nicholas II and established a provisional democratic government in the country. This kicked off a period of seismic change within Russia. Democracy was short-lived, as Vladimir Lenin led a faction of Communists–known as Bolsheviks–to overturn the just-installed government. Upon his ascension to power, Lenin created the Cheka, or secret police. This law enforcement network had the authority to execute those who didn’t comply with the government’s new rules. Among the most controversial was the nationalization of private land and factories. By 1918, civil war had engulfed the country. Civil conflict forced Russia to withdraw  its forces from World War I as Lenin hoped to stabilize the country and consolidate his power; five years later, Bolsheviks, now known as the Communist Party of the newly formed Soviet Union, defeated the so-called “Whites.” Lenin emerged from the civil conflict as the undisputed leader of the Soviet Union, controlling most of the former Russian Empire. 

1917 – 1920

World War I Influences Suffrage Movement Successes

Before the turn of the twentieth century, only one country—New Zealand—gave women the right to vote. It wasn’t until World War I that meaningful strides were made toward granting women suffrage around the world. The global scale of conflict made it necessary for women to enter the workforce. This shift highlighted a glaring injustice: that women could work and die for the war, yet they could not vote for it. In 1906, Finnish women were the first Europeans to win the right to vote. Norway (1913), Russia (1917), Britain (1918), Canada (1918), and Germany (1918) followed by granting women suffrage in short order. However, British women could not vote until the age of thirty and some Canadian women could not vote based on their race. In the United States, the passage of the Nineteenth Amendment in 1920 gave women the right to vote. However, universal suffrage was restricted due to the presence of racist laws intended to thwart political participation in Black communities. Jim Crow legislation, designed to suppress people of color, would remain in place for decades to come.

Nov 11, 1918

Armistice Day Marks Close of ‘War to End All Wars’

At 11 a.m. on the eleventh day of the eleventh month of 1918, World War I came to a halt. On a day now known as Armistice Day the Allies emerged victorious. However, the winner of World War I had little to celebrate. During four years of war, over ten million civilians and roughly nine million soldiers died. In addition to the shocking death toll, more than twenty million people were left wounded, some injured for life. In the conflict’s final year, a deadly virus later known as the Spanish Flu coursed through the world. This pandemic ultimately infected about one-third of the planet and took upwards of fifty million lives. World War I was unprecedented in many ways, but particularly in the death, carnage, and environmental destruction it caused. Known at the time as the war to end all wars, World War I proved to be the opposite. The culmination of the First World War planted the seeds for another devastating conflict just two decades later.

Jan 12, 1919

Paris Peace Conference Leads to League of Nations, Embittered Germany

Two months after World War I ended, world leaders convened in Paris to discuss the terms of peace. The war’s victors—led by the United States, Britain, and France—dominated conversations over peace terms. Multiple treaties emerged, most notably the Treaty of Versailles. This treaty forced major territorial concessions from Germany and limited its army and navy. Most consequentially, it forced Germany to accept responsibility for the war and to pay reparations for damages done to its enemies. The punitive terms of peace infuriated the German people, which fueled the rise of Adolf Hitler in the coming years. The Treaty of Versailles also established the League of Nations to serve as an international forum to promote collective security and avoid renewed conflict. The organization’s effectiveness, however, was limited by several factors, including the United States’ ultimate refusal to join.

1929 – 1939

Great Depression Creates Pre-Conditions for World War II

Before World War I, the global economy was booming. Technological advances (such as the steamship and the telegraph) coupled with trade and investment sparked an era of economic growth. Meanwhile, the relatively free movement of people without immigration limits—or passports—brought the world closer together than ever before. The postwar world, however, was a different story: countries grew protectionist, and trade and immigration restrictions followed. When the U.S. stock market crashed on October 29, 1929, the Great Depression was already starting to affect countries around the globe. The depression spread to Europe by 1931, pushing many governments toward authoritarian regimes. In Germany, the country’s economy tanked and unemployment soared. Germans were drawn toward radical anti-democratic parties on both the right (Nazis and nationalists) and the left (Communists) which promised solutions. Adolf Hitler would mix this economic desperation with his racist, toxic nationalism. This virulent, yet effective, political cocktail allowed Hitler to gain and consolidate power. Ultimately, Hitler and his Nazi Party would lead the world into a war more deadly than the first.

Sep 18, 1931

Invasion of Manchuria Signals Japanese Expansion

The worldwide embrace of post-war protectionism had a ruinous effect on global trade. Rapidly changing economic conditions put the island nation of Japan in a particular bind. Motivated by the need for food, raw materials, and new markets, the Japanese invaded Manchuria. This military campaign marked the start of Japan’s aggressive expansion campaign across East Asia and the Pacific. Though the Japanese promoted the invasion as “independence” for Manchuria, the League of Nations rejected this view and urged Japan to withdraw from the region; it withdrew from the League instead. After Japan went on to invade further parts of China in 1937, war crimes became common. One of the most horrific instances was the Rape of Nanjing, where between one hundred and three hundred thousand people were killed. In addition to the rapid killings of Chinese nationals, between twenty and eighty thousand women were sexually assaulted.

Jan 30, 1933

Hitler Named Chancellor as German Economic Situation Worsens

By 1932, almost 25% of Germany’s twenty-five million-person workforce were unemployed. The Great Depression caused severe economic pain for many Germans, creating fertile ground for the ideas of Adolf Hitler. Hitler’s Nazi Party appealed to the masses by promising to fix Germany’s broken economic system and make Germany a great power again. To gain electoral support, the party initially downplayed Hitler’s extreme views on race and exploited people’s fears of communism. In 1933, Hitler was named chancellor of Germany by conservatives in the parliament who thought they could use him politically. However, Hitler almost immediately passed legislation allowing himself to centralize power in Germany’s government. By 1934, he had become the supreme leader of the country. Shortly thereafter, Hitler eliminated all other political parties and passed the Nuremberg Laws ending civil liberties for Jewish people in Germany. Hitler also began to build up the country’s military, clearly violating the Treaty of Versailles. Hitler’s campaign of European expansion and aggression was officially underway.

Oct 3, 1935

Second Italo-Ethiopian War Demonstrates League of Nations’ Ineffectiveness

For decades, Ethiopia remained independent while European powers colonized its neighbors. To legitimize its own sovereignty, Ethiopia joined the League of Nations in 1923. However, in 1935, an emboldened Italy led by fascist dictator Benito Mussolini invaded Ethiopia. The League protested the invasion, but took little action; world leaders even declined to close the Suez Canal to Italian ships. Moreover, Italy’s usage of mustard gas against both Ethiopian military forces and civilians did little to change the League’s hands-off approach. Once again, the ineffectiveness of the League of Nations was on display. By 1936, Italy had annexed Ethiopia and merged the country with Eritrea and Somaliland into a single country known as Italian East Africa. Mussolini then signed on to the Rome-Berlin Axis, formalizing cooperation with Hitler; in 1939, this relationship was strengthened by the signing of the Pact of Steel. This pact formalized a full military alliance between Fascist Italy and Nazi Germany. 

1936

Spanish Civil War Provides Dress Rehearsal for World War II

As authoritarian or far-right governments came to power across Europe, Spain was ripe for civil conflict. In July of 1936, a coup in Spain pitted the country’s liberal and leftist Republican government against the Nationalists. The Nationalists were a group of fascist rebels led by General Francisco Franco who were eager to overthrow the Spanish Second Republic. Britain and France declined to get involved in the resulting civil war, although the Soviet Union supported the Republicans. Franco turned to Germany and Italy for aid, and Italy supplied seventy-five thousand troops, plus pilots and planes. Meanwhile, Germany used the conflict to test-run blitzkrieg, or lightning war. This military strategy was designed to overwhelm its opponents with coordinated attacks by air and on the ground. Thousands of foreign fighters traveled to Spain to fight against the advance of fascism. However, after three years of bloodshed, the fascists emerged victorious and Franco established himself as dictator. Though Spain did not join the Axis powers (Germany, Italy, and Japan) in World War II, many historians consider the Spanish Civil War as a practice for the impending global conflict.

September 1938

Britain, France Appease Aggressive Germany at Munich Conference

In the years leading up to World War II, Nazi Germany grew more aggressive both inside and outside its borders. At home, Hitler institutionalized and escalated violence against minority populations. Abroad, Germany annexed Austria, declaring their intentions for rapid territorial expansion. However, Hitler drew little response from European leaders, who instead tried to accommodate or appease him. European leaders believed that a policy of appeasement was necessary to avoid another devastating global conflict. In 1938,  leaders of Britain, France, Germany, and Italy met in Munich to discuss Germany’s desire to annex the Sudetenland, an ethnically German region in the newly formed country of Czechoslovakia. During these meetings, Britain and France—once again—declined to stop Germany’s growing aggression. By August 1939, Germany had entered into a nonaggression pact with the Soviet Union. This agreement allowed the Nazis and Soviets to divide up spheres of influence in Eastern Europe and pave the way for the two countries to invade Poland, which took place weeks later. World War II was in full swing.

May 1940–June 1941

With Eastern Europe Occupied, Nazis Decimate Western Europe

By the beginning of 1940, much of Eastern Europe was occupied by Nazi Germany and the Soviet Union (the Soviet Union had also invaded Poland and annexed and occupied land in Eastern Europe). Hitler then set his sights west, invading France through Belgium. The Germans overwhelmed the French in just six weeks. After Paris surrendered, the Nazis divided the conquered country in half. Hitler’s army occupied the north and set up a puppet government in the city of Vichy to rule the south. As Germany set its sights on an invasion of their island nation, British air forces emerged successful from the so-called Battle of Britain. Victory in this battle prevented the Germans from dominating the air over Britain and its coastal seas; German air supremacy would have enabled Hitler to carry out his invasion. Undeterred, Hitler began a bombing campaign known as the Blitz, in which British cities were attacked every night for eight months. During the Blitz, British citizens lived in terror. Many sheltered underground at night, only emerging in the day to survey the damage done and care for the wounded and dead. The Blitz campaign ended in May 1941, as stiff British resistance persuaded Hitler to divert his attention to an old friend turned foe. Hitler turned his military against the Soviet Union, which he believed had become a greater threat to his ambitions.

1941 – 1945

The Holocaust—Nazi Germany’s Systematic Mass Murder Campaign

As Nazi Germany invaded and overtook much of Eastern Europe, it forced Jewish people into ghettos with terrible living conditions. This repression escalated into organized violence on November 9, 1938—known as the Night of Broken Glass, or Kristallnacht. On this night, Nazi soldiers set fire to synagogues, schools and homes, and sent thirty thousand Jewish people to concentration camps. By late 1941, Nazis were implementing a system Hitler referred to as the “final solution to the Jewish problem.” As a result of the “final solution,” Jewish people from across Europe were gathered and sent to killing centers designed specifically for mass murder. Over the course of the war, thousands of German citizens and foreign collaborators aided the Nazis as they murdered six million Jews and millions of other persecuted people. After the war, the term genocide—the deliberate harming of a specific group of people—emerged as a key component of human rights law to describe this atrocity, which was known as the Holocaust. 

Dec 7, 1941

Japan’s Attack on Pearl Harbor Brings United States Into World War II

As fighting raged in Europe and Asia, U.S. lawmakers remained determined to stay out of World War II. In reality, though, the United States’ Lend-Lease policy, which ultimately distributed more than $45 billion in military supplies to its European and Asian friends, put the United States increasingly on the side of the democratic, anti-Fascist allies. Meanwhile, U.S. embargoes made Japan increasingly desperate for oil and other essential war materials. Economic strangulation led to Japan’s provocative decision to occupy French Indochina, neighbor to the U.S.-controlled Philippines. As last-ditch negotiations to end the embargoes faltered, Japan launched a surprise attack on a U.S. major military base in Hawaii. This attack killed more than two thousand U.S. soldiers, sank four U.S. battleships, and destroyed hundreds of aircraft. Referring to the December 7, 1941, attack on Pearl Harbor as “a date which will live in infamy,” President Franklin D. Roosevelt asked Congress for a declaration of war against Japan. Following a nearly unanimous vote in Congress, war was declared the following day; three days later, Japan’s European allies declared war on the United States. Once again, the United States found itself entrenched in another global conflict.

July 1942–February 1943

Battle of Stalingrad Signals Beginning of End for Germany

In June 1941, Nazi Germany launched the largest-scale military attack in modern history. Hitler deployed three million soldiers against the Soviet Union, violating the nonaggression pact signed between the two countries in 1939. In early victories, Germany conquered large swathes of territory. Within five months, the Nazis took over half a million prisoners of war. But then the brutal Russian winter arrived. German machines froze and fighting slowed. When it resumed in earnest the following spring, Germans attacked Stalingrad. The goal: was to seize Soviet oil fields to the south. In a battle considered the war’s turning point, the city survived Germany’s onslaught. The Soviet Union then launched a successful counteroffensive following Stalingrad’s defense. The resulting victory was not without losses: approximately two million people perished during this half-year battle. More Soviet soldiers died in this one siege than American soldiers throughout the whole war; only six percent of the captured German soldiers survived. The beginning of the end of World War II had arrived.

August 1942–February 1943

Battle of Guadalcanal a Turning Point in Pacific

Within hours of their assault on Pearl Harbor, Japanese forces attacked several Pacific countries and territories. Their targets included Hong Kong, Indonesia/the Dutch East Indies, Malaysia, Singapore, and the U.S. territories of Guam and the Philippines. After roughly half a year of Japanese momentum, the United States destroyed several of Japan’s aircraft carriers at the Battle of Midway in June 1942. Following this victory, the United States went on the offensive, setting its sights on Japanese-controlled Burma, Guadalcanal in the Solomon Islands, and the rest of the Pacific. At the Battle of Guadalcanal, Japan lost two-thirds of its soldiers during a six-month battle it ultimately lost. Following a string of victories, the United States began a campaign of strategic island-hopping toward the Japanese archipelago in 1943. Meanwhile, Japan’s Axis allies had recently faced significant losses in Northern Africa. The British scored key victories, breaking through German and Italian military lines and threatening Egypt and the Suez Canal. Allied forces also gained a key victory in El Alamein, Egypt. As the Allies gained ground in the Pacific and Northern Africa, the tide of the war began to turn in their favor.

Jun 6, 1944

Invasion of Normandy Begins World War II’s Final Act

After gains in Eastern Europe, Northern Africa, and the Pacific, the Allied forces sought to relieve pressure on the Soviet Union’s forces by attacking Germany from the South and West. In July 1943, the Allies invaded Sicily which signaled the start of the successful Italian campaign and the downfall of Benito Mussolini. After Mussolini was overthrown, the new government signed an armistice that left Germany isolated. Then, in an effort to liberate France, the Allies stormed the beaches at Normandy. Augmented by overnight parachute and glider landings, massive air attacks, and naval bombardments, the invasion on D-Day was the largest shipborne landing in history. This invasion included more than 150,000 soldiers primarily from the United States, Britain, and Canada, and approximately 7,000 naval vessels. The successful military campaign left the Allies with a hold on Normandy. Subsequent military campaigns moved through France, and by August 1944, Paris was liberated. Meanwhile, the Allies continued their attacks on Germany. In February 1945, at a point where Germany was already weakened, they began a three-day bombing of Dresden. The firebombing campaign destroyed over twelve thousand buildings and left approximately twenty-five thousand civilians dead. On May 8, 1945, Germany surrendered, ending World War II in Europe.

August 1945

Atomic Bombs Bring World War II to an End

Despite victory in Europe, war with Japan raged on. In March 1945, the United States firebombed Tokyo, flattening the city. Approximately one hundred thousand civilians were killed, and one million people were left homeless. Japan’s military leaders refused to surrender. To end the war, U.S. President Harry S. Truman was presented with two options: an invasion of Japan or the use of a new weapon. Seeking to avoid a long and costly military operation, Truman turned to the latter: the nuclear bomb. On August 6, 1945, the United States dropped the first of these singularly destructive weapons on the Japanese city of Hiroshima. The atomic bomb instantly killed an estimated 80,000 people and left over 120,000 to deal with severe burns and radiation poisoning. When the Japanese did not immediately surrender, the United States dropped another bomb on Nagasaki three days later, killing seventy-four thousand people. On August 15, 1945, the Japanese unconditionally surrendered. World War II, the deadliest conflict in history, had ended. 

The Cold War

After World War II, the United States and its allies, and the Soviet Union and its satellite states began a decades-long struggle for supremacy known as the Cold War. Soldiers of the Soviet Union and the United States did not do battle directly during the Cold War. But the two superpowers continually antagonized each other through political maneuvering, military coalitions, espionage, propaganda, arms buildups, economic aid, and proxy wars between other nations.

From Allies to Adversaries

The Soviet Union and the United States had fought as allies against Nazi Germany during World War II. However, the alliance began to crumble as soon as the war in Europe ended in May 1945. Tensions were apparent in July during the Potsdam Conference, where the victorious Allies negotiated the joint occupation of Germany.

The Soviet Union was determined to have a buffer zone between its borders and Western Europe. It set up pro-communist regimes in Poland, Hungary, Bulgaria, Czechoslovakia, Romania, Albania, and eventually in East Germany.

As the Soviets tightened their grip on Eastern Europe, the United States embarked on a policy of containment to prevent the spread of Soviet and communist influence in Western European nations such as France, Italy, and Greece.

During the 1940s, the United States reversed its traditional reluctance to become involved in European affairs. The Truman Doctrine (1947) pledged aid to governments threatened by communist subversion. The Marshall Plan (1947) provided billions of dollars in economic assistance to eliminate the political instability that could open the way for communist takeovers of democratically elected governments.

France, England, and the United States administered sectors of the city of Berlin, deep inside communist East Germany. When the Soviets cut off all road and rail traffic to the city in 1948, the United States and Great Britain responded with a massive airlift that supplied the besieged city for 231 days until the blockade was lifted. In 1949, the United States joined the North Atlantic Treaty Organization (NATO), the first mutual security and military alliance in American history. The establishment of NATO also spurred the Soviet Union to create an alliance with the communist governments of Eastern Europe that was formalized in 1955 by the Warsaw Pact.

1945–1952: The Early Cold War

The United States emerged from World War II as one of the foremost economic, political, and military powers in the world. Wartime production pulled the economy out of depression and propelled it to great profits. In the interest of avoiding another global war, for the first time, the United States began to use economic assistance as a strategic element of its foreign policy and offered significant assistance to countries in Europe and Asia struggling to rebuild their shattered economies.

British Prime Minister Winston Churchill and President Harry Truman at the famous “Iron Curtain” Speech

In contrast to American unwillingness to politically or militarily entangle itself in the League of Nations, the United States became one of the first members of the international organization designed to promote international security, commerce, and law, the United Nations. The United States also took an active interest in the fate of the colonies the European powers were having difficulty maintaining. In addition to these challenges, the United States faced increasing resistance from the Soviet Union which had rescinded on a number of wartime promises. As the Soviets demonstrated a keen interest in dominating Eastern Europe, the United States took the lead in forming a Western alliance to counterbalance the communist superpower to contain the spread of communism. At the same time, the United States restructured its military and intelligence forces, both of which would have a significant influence in U.S. Cold War policy.

The Worldwide Cold War

In Europe, the dividing line between East and West remained essentially frozen during the next decades. But conflict spread to Asia, Africa, and Latin America. The struggle to overthrow colonial regimes frequently became entangled in Cold War tensions, and the superpowers competed to influence anti-colonial movements.

In 1949, the communists triumphed in the Chinese civil war, and the world’s most populous nation joined the Soviet Union as a Cold War adversary. In 1950, North Korea invaded South Korea, and the United Nations and the United States sent troops and military aid. Communist China intervened to support North Korea, and bloody campaigns stretched on for three years until a truce was signed in 1953.

In 1954, the colonial French regime fell in Vietnam.

The United States supported a military government in South Vietnam and worked to prevent free elections that might have unified the country under the control of communist North Vietnam. In response to the threat, the Southeast Asia Treaty Organization (SEATO) was formed in 1955 to prevent communist expansion, and President Eisenhower sent some 700 military personnel as well as military and economic aid to the government of South Vietnam. The effort was foundering when John F. Kennedy took office.

Closer to home, the Cuban resistance movement led by Fidel Castro deposed the pro-American military dictatorship of Fulgencio Batista in 1959. Castro’s Cuba quickly became militarily and economically dependent on the Soviet Union. The United States’ main rival in the Cold War had established a foothold just ninety miles off the coast of Florida.

Kennedy and the Cold War

Cold War rhetoric dominated the 1960 presidential campaign. Senator John F. Kennedy and Vice President Richard M. Nixon both pledged to strengthen American military forces and promised a tough stance against the Soviet Union and international communism. Kennedy warned of the Soviet’s growing arsenal of intercontinental ballistic missiles and pledged to revitalize American nuclear forces. He also criticized the Eisenhower administration for permitting the establishment of a pro-Soviet government in Cuba.

John F. Kennedy was the first American president born in the 20th century. The Cold War and the nuclear arms race with the Soviet Union were vital international issues throughout his political career. His inaugural address stressed the contest between the free world and the communist world, and he pledged that the American people would “pay any price, bear any burden, meet any hardship, support any friend, oppose any foe to assure the survival and success of liberty.”

The Bay of Pigs

Before his inauguration, JFK was briefed on a plan drafted during the Eisenhower administration to train Cuban exiles for an invasion of their homeland. The plan anticipated that support from the Cuban people and perhaps even elements of the Cuban military would lead to the overthrow of Castro and the establishment of a non-communist government friendly to the United States.

Kennedy approved the operation and some 1,400 exiles landed at Cuba’s Bay of Pigs on April 17. The entire force was either killed or captured, and Kennedy took full responsibility for the failure of the operation.

The Arms Race

In June 1961, Kennedy met with Soviet leader Nikita Khrushchev in Vienna, Austria. (See a memorandum below outlining the main points of conversation between President Kennedy and Khrushchev at their first lunch meeting.) Kennedy was surprised by Khrushchev’s combative tone during the summit. At one point, Khrushchev threatened to cut off Allied access to Berlin. The Soviet leader pointed out the Lenin Peace Medals he was wearing, and Kennedy answered, “I hope you keep them.” Just two months later, Khrushchev ordered the construction of the Berlin Wall to stop the flood of East Germans into West Germany.

As a result of these threatening developments, Kennedy ordered substantial increases in American intercontinental ballistic missile forces. He also added five new army divisions and increased the nation’s air power and military reserves. The Soviets meanwhile resumed nuclear testing and President Kennedy responded by reluctantly reactivating American tests in early 1962.

During this meeting, President Kennedy and Premier Khrushchev discussed Soviet agriculture, Soviet cosmonaut Yuri Gagarin’s space flight, the possibility of putting a man on the moon, and their hopes that their two nations would have good relations in the future.

The Cuban Missile Crisis

In the summer of 1962, Khrushchev reached a secret agreement with the Cuban government to supply nuclear missiles capable of protecting the island against another US-sponsored invasion. In mid-October, American spy planes photographed the missile sites under construction. Kennedy responded by placing a naval blockade, which he referred to as a “quarantine,” around Cuba. He also demanded the removal of the missiles and the destruction of the sites. Recognizing that the crisis could easily escalate into nuclear war, Khrushchev finally agreed to remove the missiles in return for an American pledge not to reinvade Cuba. But the end of Cuban Missile Crisis did little to ease the tensions of the Cold War. The Soviet leader decided to commit whatever resources were required for upgrading the Soviet nuclear strike force. His decision led to a major escalation of the nuclear arms race.

In June 1963, President Kennedy spoke at the American University commencement in Washington, DC. He urged Americans to critically reexamine Cold War stereotypes and myths and called for a strategy of peace that would make the world safe for diversity. In the final months of the Kennedy presidency Cold War tensions seemed to soften as the Limited Nuclear Test Ban Treaty was negotiated and signed. In addition, Washington and Moscow established a direct line of communication known as the “Hotline” to help reduce the possibility of war by miscalculation.

Vietnam

In May 1961, JFK authorized sending 500 Special Forces troops and military advisers to assist the government of South Vietnam. They joined 700 Americans already sent by the Eisenhower administration. In February 1962, the president sent an additional 12,000 military advisers to support the South Vietnamese army. By early November 1963, the number of US military advisers had reached 16,000.

Even as the military commitment in Vietnam grew, JFK told an interviewer, “In the final analysis, it is their war. They are the ones who have to win it or lose it. We can help them, we can give them equipment, we can send our men out there as advisers, but they have to win it—the people of Vietnam against the Communists. . . . But I don’t agree with those who say we should withdraw. That would be a great mistake. . . . [The United States] made this effort to defend Europe. Now Europe is quite secure. We also have to participate—we may not like it—in the defense of Asia.” In the final weeks of his life, JFK wrestled with the need to decide the future of the United States’ commitment in Vietnam—and very likely had not made a final decision before his death.

Reasons for US involvement in Vietnam

Vietnam is a country in south-east Asia. There were a number of long-term and short-term reasons to explain why the USA became involved in Vietnam in the late 1950s.

Reason one – Vietnamese independence

Before World War Two Vietnam had been part of the French Empire.

During World War Two it had been invaded by Japan. Ho Chi Minh was the leader of the Vietminh, a resistance army that fought for Vietnamese independence.

After World War Two Ho Chi Minh captured Hanoi in 1945 and declared Vietnam independent. The French tried to take control again, but this was unpopular with the people. They were defeated by the Vietminh at Dien Bien Phu in 1954.

Peace was discussed at Geneva in 1954 and the Treaty of Geneva agreed that the French would leave Vietnam and the country would be split along the 17th Parallel until elections could be held.

The elections were never held and the country remained divided:

• North Vietnam was a communist republic led by Ho Chi Minh.
• South Vietnam was a capitalist republic led by Ngo Dinh Diem.

Reason two – Civil war

The Vietminh wanted to unite the country under communist leader Ho Chi Minh. Many of the South Vietnamese people supported Ho Chi Minh as they were unhappy with Ngo Dinh Diem.

War broke out between the North and South. From 1958 onwards, the South came under increasing attacks from communists in South Vietnam itself. They were called the National Liberation Front (NLF).

Reason three – The Domino Theory

This was the belief that if one country fell to communism, it was likely that the neighboring one would also fall – similar to a row of dominoes falling over. This had happened in Eastern Europe after 1945. China had become communist in 1949 and communists were in control of North Vietnam.

The USA was afraid that communism would spread to South Vietnam and then the rest of Asia. It decided to send money, supplies, and military advisers to help the South Vietnamese Government.

Reason four – The weak South Vietnamese Government

Diem was a corrupt leader who refused to give peasants land. He did not like Buddhism and treated the mainly Buddhist population badly. As a result, much of South Vietnam’s population was rebelling against him. The peasants wanted communism and supported the Vietminh and the NLF.

In 1963, President John F Kennedy sent 16,000 military ‘advisers’ to help the South Vietnamese army. Diem’s Government was overthrown. After this, there was no strong capitalist government in control of the South.

Reason five – The Gulf of Tonkin Incident 1964

On 2nd August 1964, North Vietnamese boats attacked a US Navy destroyer, the USS Maddox, patrolling in the Gulf of Tonkin.

Another attack on the Maddox was reported to have taken place on 4th August. Weather conditions were poor and there was doubt as to whether a real attack had taken place.

However, in Washington, the attack was presented as a fact and the incident gave the USA the excuse it needed to escalate the war.

US Secretary of Defence, Robert McNamara, withheld information about US support of South Vietnamese raids on North Vietnamese radar stations and other targets in the period leading up to the attack. Other evidence that suggested the second attack had not occurred was not passed on to the US Congress.

Gulf of Tonkin Resolution – US Congress gave President Lyndon Johnson permission to wage war on North Vietnam. The first major contingent of US Marines arrived in 1965.

For the next ten years, the USA’s involvement increased. By 1968 over half a million American troops were in Vietnam and the war was costing $77 billion a year.

Causes of Vietnam War

1883-1945 – Cochin-China, southern Vietnam, and Annam and Tonkin, central and northern Vietnam, along with Cambodia and Laos make up colonial empire French Indochina.

1946 – Communists in the north begin fighting France for control of the country.

1949 – France establishes the State of Vietnam in the southern half of the country.

1951 – Ho Chi Minh becomes leader of Dang Lao Dong Vietnam, the Vietnam Worker’s Party, in the north.

North Vietnam was communist. South Vietnam was not. North Vietnamese Communists and South Vietnamese Communist rebels, known as the Viet Cong, wanted to overthrow the South Vietnamese government and reunite the country.

Other Facts

1954 – North Vietnamese begin helping South Vietnamese rebels fight South Vietnamese troops, thus BEGINS the Vietnam conflict.

April 30, 1975 – South Vietnam surrenders to North Vietnam as North Vietnamese troops enter Saigon, ENDING the Vietnam conflict.

The war was estimated to cost about $200 billion.

Anti-war opinion increased in the United States from the mid-1960s on, with rallies, teach-ins, and other forms of demonstration.

North Vietnamese guerrilla forces used the Ho Chi Minh Trail, a network of jungle paths and mountain trails, to send supplies and troops into South Vietnam.

The bombing of North Vietnam surpassed the total tonnage of bombs dropped on Germany, Italy and Japan in World War II.

Today, Vietnam is a communist state.

US Troop Statistics

Source: Dept. of Defense

8,744,000 – Total number of US Troops that served worldwide during Vietnam
3,403,000 served in Southeast Asia
2,594,000 served in South Vietnam

The total of American servicemen listed as POW/MIA at the end of the war was 2,646. As of April 12, 2024, 1,577 soldiers remain unaccounted for.

US Deaths

Battle: 47,434
Non-Battle: 10,786
Total In-Theatre: 58,220

1.3 million – Total military deaths for all countries involved

1 million – Total civilian deaths

Timeline

May 25, 2012 – US President Barack Obama signs a proclamation that puts into effect the “Commemoration of the 50th Anniversary of the Vietnam War” that will continue until November 11, 2025. Over the next 13 years, the program will “honor and give thanks to a generation of proud Americans who saw our country through one of the most challenging missions we have ever faced.”