A civil war in Uruguay had grown out of a 1863 revolt, supported from Argentina, against the ruling Blanco Party. Brazil, the dominant power in the region, was wary of unrest on its southern border and became increasingly belligerent to the Blanco faction. Negotiations to assure protection of Brazilian citizens and interests in the revolt broke down and Brazil delivered an ultimatum that the Uruguayan leader, Atanasio Aguirre rejected. Within a week, Brazil had initiated what amounted to a state of war with Montevideo. (By John Osborne)