Zapf was sent back to the office and then to Jüterbog to train as a cartographer. After that, he went to Dijon and then Bordeaux, joining the staff of the First Army. In the cartography unit at Bordeaux, Zapf drew maps of Spain, especially the railway system, which could have been used to transport artillery had Francisco Franco not used narrow-gauge tracks to repair bridges after the Spanish Civil War. Zapf was happy in the cartography unit. His eyesight was so good that he could write letters 1 millimeter in height without using a magnifying glass, and this skill probably prevented him from being commissioned back into the army.