 Complete the following phrase:  In June 1944, the U.S. Army participated in Operation Overlord, the Allied invasion of Normandy. After heavy fighting, the Allies broke out of Normandy in July 1944. Efforts to capture the ports in Brittany proved difficult, but Allied forces quickly liberated Belgium and much of France. U.S. forces participated in the invasion of southern France Operation Dragoon in August 1944, and the airborne assault on the Netherlands Operation Market Garden in September, but logistical difficulties and German resistance slowed U.S. assaults on the Siegfried Line and in Lorraine in late 1944. In December 1944, the U.S. Army was surprised by the German 