U-42 was ordered by the Kriegsmarine on 21 November 1936 (as part of Plan Z).

In 1938, the OKM developed Plan Z, the projected construction program for the German navy.

Raeder's intention to fight a commerce war against Britain was the basis for Plan Z, which included twelve ships of the P-class design.

The revised version of Plan Z, approved on 27 July 1939, removed the P-class ships from the construction queue.

Prior to Plan Z, there were 5 high school, 5 middle schools, and the rest elementary.

Maybe you've never heard of Plan Z?

Twenty-four of these were planned under Plan Z but the three actually ordered were cancelled.

The main force of Plan Z were six H-class battleships.

The plan that's not getting talked about is Plan Z: no plan and no deal.

The military observes that he ate fire from the buildings he destroyed, and they devises "Plan Z".