William Walker (May 8, 1824 – September 12, 1860) was an American physician, lawyer, journalist and mercenary who organized several private military expeditions into Mexico and Central America with the intention of occupying the local nations and establishing slave-hold colonies, an enterprise then known as "filibustering". Walker usurped the presidency of Nicaragua in July 1856 and ruled until May 1, 1857, when he was forced out of the presidency and the country by a coalition of Central American armies. He returned in an attempt to re-establish his control of the region, and was captured and executed by the government of Honduras in 1860 while escaping the Costa Rican army after his defeat in Rivas and Santa Rosa battles by General Canas from the Costa Rican Army. These two battles marked the end of the American conquest of Central America.