By January 1944 the construction process had advanced to the point where the assembly of A4 rockets could begin. The commencement of A4 production in the Mittelwerk was accompanied by the restructuring of Camp Dora. The inmates who had survived the enervating construction labour of the fall and winter of 1943/44 were considered no longer exploitable for rocket production, as they either were too debilitated physically or lacked the professional qualifications for work on the assembly lines. New inmates were therefore brought to Dora, having been specifically selected in other concentration camps for the production of the A4 rockets. From March 1944 on, their exhausted predecessors were sent to the subcamps being established in the vicinity of Nordhausen, where they were required to work on tunnel expansion or aboveground construction sites. By the spring of 1944, Dora had thus developed into a turntable for the transfer of inmates and taken on the function of a main camp.