Russian First Army (Tannenberg Win)

The First Army (Russian: 1-я армия, 1А) was a field army of the Russian Empire mobilized in 1914 at the outbreak of World War I, under command of Lieutenant General Mikhail Alekseyev. In August 1914 it took part in the famous Battle of Tannenberg, which resulted in the first major Allied victory of the conflict, giving the Germans heavy casualties.