4. The Blitz began in London and spread to other cities and towns
Long-range navigation of the German bombers was often hampered by the notorious climate of the Channel and the British Isles, and port cities were a major target of the new German strategy, since they were easier to find and offered warehouses, docks, repair shops, and shipping as targets of opportunity. The German plan was altered to include the around-the-clock bombing of the British cities, with bombers escorted by fighters. The plan was to draw the RAF fighters into action against the slower and less agile bombers, where they would be engaged by the German fighters. Initially, the Blitz was a mostly daytime operation, but the RAF attacks on the Germans cost the Luftwaffe an inordinate amount of bombers and gradually the attacks shifted to being launched mostly at night.
The first major raid on the Port of London was launched on September 7, 1940, and did heavy damage to docks and other waterfront areas along the Thames. Further attacks in September resulted in little damage to the British in comparison to the losses sustained by the Germans. This was in part because the Germans lacked a long-range heavy bomber in their arsenal, and relied instead on medium bombers which could only deliver lighter payloads. The Germans also encountered a problem which the Allies would later face in reverse. Escorting fighters were limited in the amount of time they could engage the enemy, otherwise, they would have insufficient fuel to make it back to their bases. These factors forced the Germans to change to the concept of night bombing, despite the difficulties in navigation and bombing accuracy night operations posed.