Sweeney was awarded the Military Cross (MC) for rescuing a wounded corporal of his platoon on 7 June 1944 while under heavy fire near Escoville. Sweeney was wounded during the Battle of Normandy in July 1944 and was evacuated to England. He rejoined the 2nd Oxfordshire and Buckinghamshire Light Infantry (the 52nd) in October 1944. He served in the Ardennes and the Netherlands from December 1944 to February 1945. He served in Operation Varsity: the air assault landing over the Rhine on 24 March 1945, and took part in the advance across Germany to the Baltic sea. In October 1945 the 2nd Battalion, Oxfordshire and Buckinghamshire Light Infantry (the 52nd) was posted to Palestine, where Sweeney served during the Palestine Emergency.