It was converted into a tank destroyer battalion after the United States entered World War II.

After the United States entered World War II, the regiment was converted into the 71st Tank Destroyer Battalion on 30 January 1942.

[3] An unrelated 320th Armored Cavalry Regiment briefly existed in Ohio postwar as a reserve unit.

The distinctive unit insignia consisted of a 1 1/8 inch (2.86 cm) silver colored metal and enamel device with a shield divided in half by a gold line between blue and white with a gauntlet in the center.

The coat of arms was of a similar design except that it omitted the motto and included the Organized Reserve Minuteman crest above the shield.