The Coat of Arms adopted by the Regiment and approved by the War Department commemorates and symbolizes the principal features of the regimental history. Emblazoned on a field of Infantry Blue stands a Sea Lion grasping in its paws a rifle with bayonet fixed. Over the shield is engraved the regimental motto: "Pro Patria" (For Country) and above this stands a Polar Bear. The Sea Lion is taken from the Coat of Arms of the Philippine islands, while the Polar Bear is a reminder of the part played by the Thirty-First Infantry in Siberia.
Source: reprinted from Warrant Officer Charles D. Brown's Thirty-First U.S. Infantry Organization Day Twenty-Fifth Anniversary program. Back cover.