Following the Normandy invasion on 6 June 1944, the equivalent of seven US and French divisions were pulled out of Italy to participate in Operation Dragoon: the allied landings in southern France; despite this, the remaining US forces in Italy with other Allied forces pushed up to the Gothic line in northern Italy, the last major defensive line. From August 1944 to March 1945 the Allies managed to breach the formidable defenses but they narrowly failed to break out into the Lombardy Plains before the winter weather closed in and made further progress impossible. In April 1945 the Allies broke through the remaining Axis positions in Operation Grapeshot ending the Italian Campaign on 2 May 1945; US forces in mainland Italy suffered between 114,000 and over 119,000 casualties.