The attack of the 6th Panzer Army into the Ardennes in December 1944 failed to swiftly break the American defensive line and lost valuable time because of U.S. defensive efforts at locations like Monschau. Despite the allocation of SS panzer divisions, the 6th Panzer Army only managed a minor penetration into the northern defensive sector of the U.S. VIII Corps and its advance was thereafter checked by U.S. reinforcements arriving on the northern flank of the offensive.[3] After the Ardennes Offensive, the 6th Panzer Army was transferred to Hungary, where it fought against the advancing Soviet Army.