The Atlantic stops being a barrier.

Atlantic exploration required new technology. The Portuguese caravel combined square and lateen sails so it could tack against the wind. The astrolabe (improved by Muslim astronomers) measured latitude. The magnetic compass (Chinese invention) gave direction at sea. Improved cartography (Mercator projection, 1569) flattened the globe usefully. Ship cannons let small Portuguese craft challenge larger fleets. None of this would have mattered without Atlantic prevailing winds and currents that made return voyages possible. Combined, these technologies turned the Atlantic into a connector instead of a barrier.

Causes: Ottoman control of eastern trade routes after 1453 made western alternatives valuable. Renaissance curiosity, monarchic centralization (Ferdinand and Isabella in Spain), and joint-stock financing all aligned. Events: Henry the Navigator’s school at Sagres trained Portuguese sailors; Bartolomeu Dias rounded the Cape of Good Hope (1488); Vasco da Gama reached India (1498); Columbus sailed for Spain (1492); Magellan’s crew circumnavigated (1519–1522). Northern European powers (Netherlands, England, France) followed in the 1600s with chartered trading companies.

The Columbian Exchange moved life forms in both directions. To Europe: maize, potatoes, tomatoes, peppers, tobacco, cacao, syphilis, silver. To the Americas: wheat, rice, sugar, horses, cattle, pigs, smallpox, measles, typhus. Demographic effect: Eurasian crops fed a population boom in Europe and Asia; Eurasian diseases killed 50–90% of indigenous Americans within a century. The exchange was profoundly asymmetric—biology favored the colonizers. Forced African migration via the slave trade was the human leg of the exchange.

Spain built the first transatlantic empire on indigenous labor and Andean silver (Potosí). Portugal’s empire was strung along coasts: Brazil for sugar, Mozambique and Goa for Indian Ocean trade. The Dutch Republic’s VOC (1602) dominated the spice trade and South African Cape colony. England’s East India Company would become the empire-on-the-cheap that took over India. France competed in Canada, Louisiana, and the Caribbean. Joint-stock companies, royal charters, and naval power were the institutions of empire.

About 12.5 million Africans were forcibly transported across the Atlantic between 1500 and 1867; ~10.7 million survived the Middle Passage. African coastal states (Asante, Dahomey, Kongo) became enmeshed in slave-raiding economies—exporting captives in exchange for European firearms, which fueled more raiding. The trade depopulated parts of Central and West Africa, distorted gender ratios, and entrenched warrior elites. Some leaders resisted (Queen Nzinga of Ndongo); most adapted to a system whose worst costs they couldn’t see across the Atlantic.

Across Eurasia and the Americas, states faced rebellions and crises. England’s civil war (1642–1651) executed a king. Cossack revolts shook Russia. Maratha Confederacy fractured the Mughal Empire. Tokugawa Japan barely contained peasant uprisings (ikki). In the Americas, slave revolts—small ones constantly, larger ones occasionally (Stono 1739, Haiti 1791)—and indigenous resistance (Pueblo Revolt 1680) all challenged colonial control. The era’s expanding empires were also vulnerable empires.

Spanish America’s casta system codified racial hierarchy: peninsulares > creoles > mestizos > mulattos > indigenous and Africans. Casta paintings depicted the racial mathematics of empire. In Atlantic slave societies, race and slavery fused into chattel slavery: heritable, lifelong, and racially defined. European women lost public roles as states centralized; non-elite women in colonies worked the plantations and the markets. Gender, race, and class were the three intersecting hierarchies the system enforced.

The biggest CHANGE was integration: by 1700, silver from Potosí flowed to Ming China; tobacco moved to Ottoman courts; sugar from the Caribbean fed European and Asian luxury markets. The biggest CONTINUITY was that most states were still agrarian, monarchic, and religiously legitimated—just operating now within a global economy. The Industrial Revolution and Atlantic Revolutions of Unit 5 would break the second pattern; the global economy itself would only deepen.

Strong comparisons: Spanish vs. Portuguese empire structure (territorial vs. coastal); maritime empires vs. land-based gunpowder empires (cannon-armed ships vs. cannon-armed armies); Atlantic vs. Indian Ocean systems (slave-plantation vs. spice-trade extraction); state-led empire (Spain) vs. company-led empire (VOC, EIC). The comparison FRQ rewards 2 similarities, 2 differences, and a causal explanation for at least one of them.