Selected for production over the competing GB-2 and GB-3 due to its simpler control system and its proving more practical for bomber carriage, production of the GB-1 began in May 1943; arriving in the combat zone in September, operational use was delayed due to the limited bombload the glider imposed – a B-17 Flying Fortress bomber could carry only two GB-1s on a mission, one on a rack under each of the bomber's wings – and the accuracy of the GB-1 proving to be significantly worse than that of ordinary bombs. Despite this, by May 1944 the first releases of GB-1s were undertaken. On 28 May 1944, 42 of 113 glide bombs released hit Cologne, after being released 18 miles from the Eifeltor marshaling yard in the city at ; many failed to hold an electrical charge in their batteries, causing their autopilots to fail. German gunners mistook the bombs for aircraft they were shooting down, claiming over 90 kills. Due to the inaccuracy the bombs demonstrated, the Eighth Air Force did not use the glide bombs again; however other units would go on to use over a thousand GB-1s before the end of the war.