After the German declaration of war against the United States on Dec 11, 1941, the Ritchie Boys became an important weapon for the Allies. Many of them entered Europe on D-Day, 6 June 1944. Others followed over time. Shortly after reaching land, they left their units and pursued their special tasks. They were able to feed the Allies valuable information. Gen. Oscar Koch (Gen. Patton's G-2) acknowledged that the advance warning of the German Bulge offensive was made possible by information gathered by their MIS units. Moreover, the Ritchie Boys helped break German resistance by demoralizing them in both open and covert operations. They interrogated POWs and defectors to obtain information about German force levels, troop movements, and the physical and psychological state of the Germans. A common interrogation tactic was to use the Germans' fear of transfer into Soviet custody. By means of targeted disinformation via newspaper announcements, flyers, radio broadcasts, and sound trucks, the German population and military were encouraged to cease their resistance to the Allied invasion.