The 4th Battalion, 31st Infantry Regiment ("Polar Bears") has a distinguished history dating back to its activation in 1916. The unit first saw combat during World War I in Siberia as part of the American Expeditionary Force, and later fought in the Philippines during World War II, earning the nickname "Manchu" for its service in China. In Vietnam, the 4-31 Infantry participated in numerous operations, demonstrating valor and resilience. In recent decades, the battalion has deployed to Iraq and Afghanistan, continuing its tradition of excellence as part of the 10th Mountain Division.