Complex sentence: U- 869 had been previously ordered by Karl Dönitz to move her area of operations from the North American coast to the Gibraltar area, and for many years this attack was assumed to have been her end.
Split into simpler sentences: U- 869 had been previously ordered by Karl Dönitz to move her area of operations from the North American coast to the Gibraltar area. For many years this attack was assumed to have been her end.