Stephen Roskill 
Churchill and the Admirals [EPUB ebook] 

Winston Churchill enjoyed two stints as First Lord of the Admiralty, at the start of the First World War and at the start of the Second. He retained close interest in naval matters, especially as the defeat of the U-boat menace was so vital in both wars to maintain the vital supplies so necessary for Britain’s war efforts. Indeed, Churchill later said that this was the only thing that had threatened the ultimate Allied victory.