The term National army has many meanings around the world, and is used in many nations, typically to mean the lawful army of the state as disctinct from rebel armies or private armies that may operate there.

National Army may also refer to:

• In the United States of America, the National Army (USA) is the 1917 army.
• In the Irish Free State, it was the Regular Army of the new state, being previously the revolutionary Irish Republican Army. It subsequently became the Irish Defence Forces of the Republic of Ireland.

Military