[down and out]

In July 1943, the idea was again resurrected after Germany had successfully developed the V-1 rocket. The Vergeltungswaffen 1 (Vengence Weapon 1) was an unmanned flying bomb, powered by a pulse-jet with a range of 148 miles (238km). It was designed to be launched from a land installation but the idea of using U-boats as a launch platform was proposed. The notion was to provide the weapon with mobility, where it could strike almost any city in the world. The V-1 however was a Luftwaffe weapon and the idea was again rejected.

http://www.uboataces.com/articles-rocket-uboat.shtml