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)