The size of the German force was less than a quarter of what Schmid had originally hoped could be mustered. One source referred to "Gisela" as the swansong of the German night fighter force. During the course of the operation, the last German aircraft to be brought down over British soil crashed. Some historians have claimed that had German intruder operations been maintained over Britain in 1941, and thereafter, the British night flying training program, which produced the nucleus of the huge bomber force that operated in 1944–45, could have been halted or disrupted. The decision not to continue intruder operations, in their view, allowed the British to build their bomber force virtually unhindered for over four years. A consequence of an effective German intruder campaign at this time may have given the "Luftwaffe" night fighter defences an unassailable lead in the night war, and may have stopped, or diminished, the effectiveness of British bombing operations. This omission could be regarded as one of the major errors made by the OKL concerning the air defence of Germany. In the last eight weeks of the war the bombing intensified until British bombing operations were suspended in late April 1945. By this time, most of the German airfields were under threat from the advancing Allied ground forces and the mass surrender of the "Nachtjagd" was taking place.