An "army commander" refers to a high-ranking military officer who leads and controls a specific army. They are responsible for making decisions and directing troops on the battlefield. Full definition
The earliest account of a bright night comes from Pliny the Elder, a Roman army commander who studied nature in his spare time. (newscientist.com)
So he sent a trusted army commander to Egypt, to marry Shajar and rule as Sultan. (avocadobravado.net)
The local army commander, General Dyer, marched a troop of Indian soldiers — who were mainly Gurkhas with some Baluchis - to the square. (politics.co.uk)