In the new century, as wars became less violent and less frequent, Brazil entered into a small conflict with Bolivia for the possession of the Acre, which was acquired by Brazil in 1902. In 1917 Brazil declared war on the Central Powers, joined the allied side in the First World War and sent a small fleet to the Mediterranean Sea and some troops to be integrated with the British and French forces in the region. Brazil was the only South American country that participated in the First World War. Later in 1932 Colombia and Peru entered a short armed conflict for territory in the Amazon. In the same year Paraguay declared war on Bolivia for possession of the Chaco, in a conflict that ended three years later with Paraguay's victory. Between 1941 and 1942 Peru and Ecuador fought decisively for territories claimed by both that were annexed by Peru, usurping Ecuador's frontier with Brazil.