After the Battle of the Bulge, in early 1945 Allied armies advanced into the Rhineland in preparation for a massive assault into the heart of the Reich. Worms was a German strongpoint on the west bank of the Rhine and the forces there resisted the Allied advance tenaciously. Worms was thus heavily bombed by the Royal Air Force and the U.S. Army Air Forces in two attacks on Feb. 21 and March 18, 1945, respectively. A post-war survey estimated that 39 per cent of the town's developed area was destroyed. The RAF attack on Feb. 21 was aimed at the main railway station on the edge of the inner city, and at chemical plants southwest of the inner city, but also destroyed large areas of the city centre. Carried out by 334 bombers, the attack in a few minutes rained 1,100 tons of bombs on the inner city, and Worms Cathedral was among the buildings set on fire. The Americans did not enter the city until the Rhine crossings began after the seizure of the Remagen Bridge.