Landing at Utah-Beach on June 8, 1944, Major Hamilton commanded the 1st Battalion (about 800 men) of the 357th Regiment of the 90th US Infantry Division during the fighting for the liberation of Périers.
Ed was a leader of men. On August 7, a few kilometers from Le Mans, his regiment decimated a unit of German soldiers, making 30 dead, 80 wounded and 280 prisoners. The following September 8th, in Meurthe-et-Moselle, he launched a new raid on the German positions which resulted in the destruction of 4 enemy tanks and the capture of 17 prisoners. This new action earned him the Distinguished Service Cross for his heroic behavior under enemy fire. Promoted Lieutenant-Colonel, he is seriously wounded on September 10th at Hayange, in Moselle.