In 1937/38 the development of a big destroyer for Atlantic operation started. Being about 50% bigger than all previous destroyers those ships should be equipped with a mixed propulsion system like the one uses in the Light Cruisers of the Köln
Class: Diesel engines for long cruises and turbines for fast combat operations. To protect the ships, even a light armor protection was projected.
Although the design was not very satisfying, 24 of this ships were projected for the Z-Plan , 10 should be build until 1943, the other 14 should be completed until 1945. Three ships were actually ordered in 1939 but canceled in 1940 without being laid down.
The development of the big destroyers continued and lead later to the design of the Spähkreuzer.