Second Army or 2nd Army may refer to:
Germany 2nd Army (German Empire), a World War I field army 2nd Army (Wehrmacht), a World War II field army 2nd Panzer Army
Russia / Soviet Union Second Western Army, fought in the French invasion of Russia 2nd Army (Russian Empire), fought at Tannenberg in 1914 2nd Army (RSFSR), fought in the Russian Civil War 2nd Ukrainian Soviet Army, fought in the Russian Civil War 2nd Red Banner Army, a Soviet field army of World War II
Others II Army (Argentina) Second Army (Australia) 2nd Army (Austria-Hungary) Second Army (Bulgaria) Second Army (Egypt) Second Army (France) Second Army (Hungary) Second Army (Italy) Second Army (Japan) Second Army (Ottoman Empire) Second Army (Poland) Second Army (Romania) Second Army (Serbia) Second Army (Turkey) Second Army (United Kingdom) Second Army (Home Forces), also in the United Kingdom 2nd Army (Kingdom of Yugoslavia) Second United States Army
See also II Corps (disambiguation) Second Army Corps (Spanish-American War) 2nd Guards Army 2nd Guards Tank Army 2nd Division (disambiguation) 2nd Brigade (disambiguation) 2nd Regiment (disambiguation)