Complex sentence: Vulkan Docks in Stettin was contracted to build a prototype in March or April 1945 but little work took place before Germany's final collapse and it is unlikely that the system would have been successful if it had been completed.
Split into simpler sentences: Vulkan Docks in Stettin was contracted to build a prototype in March or April 1945 but little work took place before Germany's final collapse. It is unlikely that the system would have been successful if it had been completed.