 Flying Fortresses took part in the bombardment of the Italian stronghold of Pantelleria, the invasion of Sicily and the invasion of Italy.Once the Allies were firmly established on the Italian mainland, the B-17 squadrons moved Italy, joining the Fifteenth Air Force in November 1943 and were upgraded to B-17Gs.They were joined by two more groups (463d, 483d) in the spring of 1944, bringing the total up to six.