  The first three production Ju 188 E-1 machines were delivered with BMW engines in February 1943, another seven in March and eight in April. A conversion testing unit was formed up in May and after testing were attached to an operational unit, with the first mission, an attack by three Ju 188E-1s on a factory in Lincoln, Lincolnshire taking place on 18 August 1943.[3] By the end of the year, 283 Ju 188s had been delivered (including Ju 188Fs) and two new factories were added to the production effort.[4] Most operational machines differed from the prototypes only in having a 20 mm MG 151/20 cannon in the nose and dorsal turrets in place of the 13 mm (.51 in) MG 131. The MG 131 I was intended to be used in the Ju 188 E-1 or the G-2 but the heavy armament in the A and E series was the MG 151/20.[5] The Ju 188 E-2 was built as a torpedo-bomber but was identical to the Ju 188 A-3.[6]
