These forces were created by Congress in 1917 as a result of the state National Guards' being deployed and were known as Home Guards. In 1940, with the onset of World War II and as a result of its federalizing the National Guard, Congress amended the National Defense Act of 1916, and authorized the states to maintain "military forces other than National Guard."[24] This law authorized the War Department to train and arm the new military forces that became known as State Guards.