First Army (under General Bradley) and British Second Army (General Dempsey), which together comprised General Montgomery’s 21st Army Group, new england kit had gained a foothold at the five main landing beaches. The seaborne operation — Operation Neptune — was preceded by a large-scale airborne assault during the night of June 5-6 into the inland areas beyond and on the flanks of the landing beaches. They were preceded by heavy air bombing and more than two hours of naval bombardment. Operation Overlord, the Allied invasion of mainland Europe and the establishment of the second front long advocated by Stalin to relieve pressure on the Russians in the East, was the greatest amphibious landing operation in history.