On 15 July 1940, the 1st Armored Division, largely an expanded and reorganized version of the 7th Cavalry Brigade, was activated at Fort Knox under the command of Major General Bruce Magruder. The 1st Cavalry Regiment was re-designated as the 1st Armored Regiment and the 13th Cavalry Regiment was re-designated as the 13th Armored Regiment under the 1st Armored Brigade, 1st Armored Division. For more than two years after its activation, the 1st Armored Division trained at Fort Knox and the division pioneered and developed tank gunnery and strategic armored offensives while increasing from 66 medium-sized tanks to over 600 medium and light armored vehicles.