Since the problems with the Do It meant that no great numbers would be built in the foreseeable future. JunkeTs received an order to convert the Ju 52 three-engined airliner into an improvised bomber. The JunkeTs works at Dessau began conversion of the first Ju 52/3m in 1934. The Auxiliary Bomber Group 1, founded in January of the same year under the guise of a Lufthansa inspectorate, was equipped in March 1934 with three Do 11's and 24 Ju 52/3ms. From the middle of 1934 mass production of the Ju 52/3m began. The basic airframe was the same as that of the civilian version, and its armament consisted of one movable dorsal MG 15 machine gun on the rear fuselage and another in a retractable 'dustbin' in the cabin floor. The bomb load was 1,500kg. Officially, the Ju 52 K was as a bomber, although it was more of a solution to an embarrassment, since suitable aircraft were not available initially. At this time Bomber Group (KG) 154 was established, and on 15th March 1936 it was followed by KG 152. These were renamed KG I Hindenburg on 1 May 1939. They were followed by KG 253, equipped with Do 23s and Ju 86s, and by KG 155 in the early part of 1937. It was intended to equip this last group solely with the Do 17 E. but it eventually also received Ju 5213ms. In August and September 1938 the Staff and I./KG 252 were established at Cottbus, and II./KG 252 was created as a second group from the existing IV./KG 153. Because of its ruggedness, the Ju 52 took on a significance far in excess of that initially envisaged during the Luftwaffe's formative years. From the end of 1935 up to the introduction of the He III and Ju 86 medium bombers, almost two-thirds of the operational aircraft of the Luftwaffe bomber force were 1u 52/3ms. In all, 760 were delivered. The Ju 52/3m g3e could also be used as a night bomber. It had improved radio direction finding equipment and a better bomb-release mechanism. An export version, the Ju 52/3m g4e, had the same power plant and equipment, and differed only in having a tail wheel instead of the earlier skid. Most examples of this variant were taken over by the Luftwaffe, and only a few went abroad. The Ju 52 first saw active service as a transport and bomber in the Spanish Civil War. Before the beginning of the Second World War the majority of the remaining Ju 52 auxiliary bombers were reconverted to serve in the transport role by removal of their lower gun mountings.