The first 8th Air Force Mission over Germany was on 27 January, 1943. The 1st and 2d Bombardment Wings (64 B-17 and 27 B-24) attacked the Wilhelmshaven, Germany Naval Base. Source: 8th AF Historical Society

The first ground combat took place on 12 September, 1944 near Hemmeres, Germany, involving elements of Combat Team 22, 4th Infantry Division (22nd Regimental Combat Team with reinforcements, along with war corespondent Ernest Hemingway). A patrol from Combat Team 22 had crossed the Our River into Germany the night of the 11th and recovered a sample of German soil. On the 12th, a strong combat patrol under LT E.C. Martin (Three tanks, two tank destroyers, six Jeeps, and platoon of riflemen) crossed the Our River around noon and were involved in several firefights. They destroyed one tank and one personnel carrier, damaged a second tank, and captured three prisoners. A second patrol also crossed into Germany around the same time. Source: Seize, Occupy and Defend, by Robert & Katherine Bailey.