The siege was the bloody centerpiece of the Uruguayan Civil War, a feud between two factions that still define the country's politics: the Colorados, who held Montevideo, and the Blancos under Oribe, who held nearly everything else. The quarrel had metastasized into an international war, drawing in the Argentine strongman Juan Manuel de Rosas, the Empire of Brazil, France, and Britain. For most of those nine years Uruguay effectively had two capitals. The Defense Government ruled from inside the besieged city. Oribe ruled the countryside from the Cerrito de la Victoria, a low hill on the outskirts, governing as though the war were already won.

By 1843 Montevideo had been transformed by a decade of immigration, and native-born Uruguayans made up only about a third of its population. When Oribe closed the ring, the city's defenders organized themselves by homeland into volunteer legions: an Argentine legion, a Basque legion, French battalions, a Montevidean battalion, and battalions of free Africans. There was also an Italian legion, and at its head stood Garibaldi. These were not professional soldiers but shopkeepers, dockworkers, and craftsmen defending the streets where they lived. Their numbers outstripped the native Uruguayan troops, and their stubborn, improvised resistance gave the siege its legend - and gave Dumas his comparison to Troy.

Garibaldi's men became famous for a uniform that began as an accident of commerce. A Montevideo merchant house held a stock of red woolen shirts originally meant for the saladeros - the cattle-slaughtering and salting plants of the River Plate - where the deep color helped hide the blood of the work. The Buenos Aires market for them had been shut by the wartime blockade, so the cheap shirts were sold off and handed to the Italian volunteers. The red shirt, first worn in battle here in the early 1840s, would follow Garibaldi back to Europe and become the emblem of Italian unification. A symbol of one nation's birth was first stitched together in the besieged streets of another.

Garibaldi's Uruguayan years were not all stalemate behind the walls. In 1846, leading a few hundred volunteers of the Italian Legion, he fought an action at San Antonio that would burnish his reputation across Europe. Heavily outnumbered, his small force held its ground through a long day's fighting and withdrew intact - the kind of defiant, against-the-odds stand that turned a political exile into a romantic hero. The man who learned irregular war on these plains and rivers would carry those lessons home, and within two decades he would use them to help forge the Kingdom of Italy. The siege of Montevideo was, in a real sense, his apprenticeship.

The deadlock held until 1851, when the diplomacy finally shifted. Brazil committed to intervene on the Defense Government's side, and Justo Jose de Urquiza, governor of Argentina's Entre Rios province, broke with Rosas and joined the coalition. As armies converged and his own troops deserted, Oribe saw that the cause was lost. On 19 October 1851 he surrendered without a final battle, ending the longest siege the city had ever endured. The peace reshaped the region: Brazil gained lasting influence over Uruguay, and the victorious allies turned next toward Argentina to topple Rosas himself. Montevideo, battered but unbroken, had outlasted its besiegers.