The imperial government conspires with Buenos Aires…

The imperial government conspires with Buenos Aires authorities in the mid-1860s to replace the Blanco regime in Montevideo with a Colorado one.

The Blancos appeale to Paraguayan dictator Francisco Solano Lopez (president, 1862-70), who harbors his own fears of the two larger countries and who regardsa threat to Uruguay as a menace to Paraguay.

A small landlocked country, Paraguay has the largest army in the region: sixty-four thousand soldiers compared with Brazil's standing army of eighteen thousand.

In 1864 Brazil and Argentina agree to act together should Solano Lopez attempt to save the Blancos.

In September 1864, wrongly convinced that he would not be so foolish, the Brazilians send troops into Uruguay to put the Colorados in power.

Each side has miscalculated the intentions, capabilities, and will of the other.

Paraguay reacts by seizing Brazilian vessels on the Rio Paraguai and by attacking the province of Mato Grosso.

Solano Lopez, mistakenly expecting help from anti-Buenos Aires caudillos, sends his forces into Corrientes to get at Rio Grande do Sul and Uruguay and finds himself at war with both Argentina and Brazil.

In May 1865, those two countries and Colorado-led Uruguay sign an alliance that aims to transfer contested Paraguayan territory to the larger countries, to open Paraguayan rivers to international trade, and to remove Solano Lopez.

By September 1865, the allies have driven the Paraguayans out of Rio Grande do Sul, and they take the war into Paraguay when that country spurns their peace overtures.