Political map of South American nations 19 July 1918 (South America in the Great War): When World War I broke out in Europe, the German East Asia Squadron attempted to reach the Atlantic via the Pacific and Cape Horn, raiding merchant ships along the route. After the squadron was defeated off the Falkland Islands in late 1914 (Battle of the Falkland Islands), German submarine attacks (U-boat Campaign (World War I)) became the main threat to South American trade and shipping. In 1917, primarily in response to the intensification of submarine warfare, Brazil joined the United States and became the only South American state to declare war on Germany (Brazil during World War I). Nonetheless, the war saw the erosion of European power in South America and the accompanying rise of US influence there.