The collar insignia replicate bronze collar disks worn by enlisted soldiers in the First Division.
The origins of the “Big Red One” patch are disputed. One legend says that First Division supply trucks were painted with a red “1” to distinguish them from other country’s vehicles, and the practice carried over to shoulder sleeve patches.
A more colorful tale about the origin of the patch involves an exchange between a general (or colonel) and a lieutenant over red underwear. According to this version, the general, thinking that the 1st Division needed a shoulder sleeve insignia, cut a crude red “1” from an old pair of flannel underwear.