The Magellan War, also known as the War of 1900 or the Tierra del Fuego War, was a brief war fought in 1900 between Argentina and Chile for control over the Straits of Magellan and the Beagle Passage. After 45 days of fighting, they eventually signed the Treaty of Chilean-Argentine Agreement, which drew the border straight through the Strait and made all of the Island of Tierra del Fuego Argentine territory, along with Dawson Island. However, the treaty also solidified Chilean control over the southern side of the Beagle Passage. Border disputes along the Andes and in Patagonia were also settled by the war.
The war led to wider notoriety for future Argentinean Presidents José Felix Uriburu and Agustín Pedro Justo, both of whom served in the war as army officers.