It is widely believed that Japan's opening gambit in World War II was conceived by Admiral Yamamoto, Commander-in-Chief of Imperial Japan. However, this book sets out to show that it was the British naval authority, Hector C. Bywater, who first spelled out the war plan adopted by Yamamoto in his strategy entitled The Great Pacific War. Yamamoto read Bywater's book while Naval Attache in Washington, reported on it to Tokyo, and was consequently charged with developing a war contingency plan in 1939. He was soon obliged to carry it out. Bywater's life is presented against a pageant of naval history from the first testing of high-speed armoured warships at the Battle of the Yalu River in 1894, up to World War II.