By the Spring of 1944, the Allied preparations for the invasion of France and the initial stages for the liberation of western Europe (Operation Overlord) were complete. They had assembled around 120 Divisions,consisting of over 2 million men, of which 1.3 million were Americans, 600,000 were British and the rest Canadian, Free French and Polish. The invasion, code-named Operation Neptune but commonly referred to as D-Day, was set for June 5th but bad weather postponed the invasion to June 6, 1944. Almost 85–90% of all German troops were deployed on the Eastern Front and only 400,000 Germans in two armies, the German Seventh Army and the newly-created Fifth Panzer Army, were stationed in the area. The Germans had also constructed an elaborate series of fortifications along the coast called the Atlantic Wall, but in many places the Wall was incomplete. The Allied forces under supreme command of Dwight D. Eisenhower had launched an elaborate deception campaign to convince the Germans that the landings would occur in the Calais area which caused the Germans to deploy many of their forces in that sector. Only 50,000 Germans were deployed in the Normandy sector on the day of the invasion. The invasion began with 17,000 airborne troops being dropped in Normandy to serve as a screening force to prevent the Germans from attacking the beaches. During the early morning, a massive naval flotilla bombarded German defenses on the beaches, but due to lack of visibility most of the shots missed their targets. Additionally, most of the troop transport ships (with personnel, trucks, and equipment) were off-course, some as much as thousands of yards from their respective landing zone amongst the five beach areas (Utah, Omaha, Sword, Juno and Gold). The Americans in particular suffered heavy losses on Omaha beach due to the German fortifications being left intact. However by the end of the first day, most of the Allied objectives were accomplished even though the British and Canadian objective of capturing Caen proved too optimistic. The Germans launched no significant counterattack on the beaches as Hitler believed the landings to be a decoy. Only three days later the German High command realized that Normandy was the actual invasion, but by then the Allies had already consolidated their beachheads. The bocage terrain of Normandy where the Americans had landed made it ideal ground for defensive warfare. Nevertheless, the Americans made steady progress and captured the deep-water port of Cherbourg on June 26, one of the primary objectives of the invasion. However, the Germans had mined the harbor and destroyed most of the port facilities before surrendering, and it would be another month before the port could be brought back into limited use. The British launched another attack on June 13 to capture Caen but were held back as the Germans had moved in large number of troops to hold the city. The city was to remain in German hands for another 6 weeks. It finally fell to British and Canadian forces on July 9. Allied firepower, improved tactics, and numerical superiority eventually resulted in a breakout of American mechanized forces at the western end of the Normandy pocket in Operation Cobra on July 23. The allied advance to this point had been considerably slower than expected. Seven weeks after D-Day, U.S. First Army was holding an east-west line that ran from Caumont to Saint-Lô to Lessay on the Channel. Pre-D-Day projections had put the Americans on that line by D Plus Five  . When Hitler learned of the American breakout, he ordered his forces in Normandy to launch an immediate counter-offensive. However the German forces moving in open countryside were now easily targeted by Allied aircraft, as they had initially escaped Allied air attacks due to their well camouflaged defensive positions. The Americans placed strong formations on their flanks which blunted the attack and then began to encircle the 7th Army and large parts of the 5th Panzer Army in the Falaise Pocket. Some 50,000 Germans were captured, but 100,000 managed to escape the pocket. Worse still, the British and Canadians—whose initial strategic objective to draw in enemy reserves and protect the American flanks so as to promote a later turning movement north had been achieved —now began to break through the German lines. Any hope the Germans had of containing the Allied thrust into France by forming new defensive lines was now gone. The Allies raced across France, advancing as much as 600 miles (1,000 km) in two weeks The German forces retreated into Northern France, Holland and Belgium. By August 1944, Allied forces stationed in Corsica launched Operation Dragoon, invading the French Riviera on August 15 with the 6th Army Group, led by Lieutenant General Jacob Devers), and linked up with forces from Normandy. The clandestine French Resistance in Paris rose against the Germans on August 19, and the Free French 2nd Armored Division under General Philippe Leclerc, pressing forward from Normandy, received the surrender of the German forces on behalf of General von Choltiz from Paris and liberated the city on August 25. Around this time the Germans began launching V-1's (known as the "buzz bomb"), the world's first cruise missile, at targets in southern England and Belgium. Later they would employ the much-larger V-2 rocket, a liquid-fuelled guided ballistic missile. These weapons were inaccurate and could only target large areas such as cities; they had little military effect and were intended to demoralize and/or terrorize Allied civilians.