The 1st Army Corps (Russian: 1-й армейский корпус) was a formation in the Imperial Russian Army, formed in the 1870s. It took part in the Russo-Turkish War of 1877—78, and later, in August 1914, the 1st Army Corps fought as part of the Second Army in the Battle of Tannenberg. There, it was defeated by the Germans along with the rest of the Second Army. During the rest of World War I, it took part in other operations, up until around 1918.