The division then joined the II Corps's notional move south from Scotland to England, in June 1944, becoming part of "Fortitude South" to convince the Germans that the Normandy landings were a feint and the main Allied invasion would take place in the Pas-de-Calais with a force of 500,000 men. The deception aimed to persuade the Germans not to move the 18 divisions of the 15th Army from the Pas-de-Calais to Normandy. The division also provided the signal and headquarters staff to create the phantom 55th US Infantry Division. In July, the division was reported as an assault division training near Southampton. In September, as the "Fortitude" deception was wound down and the Fourth Army dispersed, it was allowed to be known that the division had reverted to a training role. Historian Gerhard Weinberg wrote that the Germans readily believed in the threat to the Pas de Calais and "it was only at the end of July" that they realised a second assault was not coming, and "by that time, it was too late to move reinforcements". Nevertheless, Barbier concludes "that the importance of the deception has been overrated". The 15th Army was largely immobile, and not combat-ready. Despite the deception, several German divisions, including the 1st SS Panzer Division in reserve behind the 15th Army, were transferred to Normandy. The Germans had realised, as early as May, that the threat to Normandy was real. Barbier concluded that while the Germans believed the deception due to "preconceived ideas about the importance of the Pas De Calais", the Allied staff had overestimated the effectiveness of the deception in causing the inaction of the 15th Army, because they also held a "preconceived notion of what [Operation Fortitude] would accomplish".