War Mothers observe Mother's Day at Tomb of Unknown Soldier. Washington, D.C., May 9. Scene at the Tomb of America's Unknown Soldier in Arlington National Cemetery today as thousand of war mothers from all parts of the country paid tribute to the world war hero in observance of Mother's Day. The services were conducted under the auspices of the American War Mothers at their thirteenth annual Mother's Day ceremonies, 5/9/1937