He served in the militia campaign against the Cherokee Indians in 1760-1761. When the revolution started, he sided with the rebel militia, and was made a Captain. He rose to the rank of Brigadier General during the war. On February 14, 1779, he was part of the rebel militia victory at the Battle of Kettle Creek in Georgia.
Andrew was captured and later paroled at the Siege of Charleston in 1780.When the British didn't honor the terms of his parole, he returned to militia service.