Poles provided significant contributions to the Allied effort throughout the war, fighting on land, sea and air. Particularly well-documented was the service of 145 Polish pilots flying British planes under British Command during the Battle of Britain, 79 in mixed Squadrons under the RAF after July 1940, 32 of wholly Polish Squadron 303 after 31 August 1940 and 34 also of entirely Polish Squadron 302. Other instances of service flying French planes in the Polish Air Force took place during the Battle of Britain at the same time and from 1944 the Polish Air Force (also with British planes) was established in Britain. Polish ground troops were present in the North Africa Campaign (siege of Tobruk); the Italian campaign (including the capture of the monastery hill at the Battle of Monte Cassino); and in battles following the invasion of France (the battle of the Falaise pocket; an airborne brigade parachute drop during Operation Market Garden and one division in the Western Allied invasion of Germany). Polish forces in the east, fighting alongside the Red army and under Soviet command, took part in the Soviet offensives across Belarus and Ukraine into Poland, across the Vistula and towards the Oder and then into Berlin. Some Polish contributions were less visible, most notably the prewar and wartime deciphering of German Enigma machine codes by cryptologists Marian Rejewski and his colleagues. The Polish intelligence network also proved to be of much value to the Allied intelligence. The Polish forces as a whole may be considered to have been the 4th largest Allied army in Europe, after the Soviet Union, United States and Britain.