As the major powers engaged in an arms race in the early years of the 20th century, the Admiralty was tasked with developing that deadly stalker of the high seas - the submarine. In 1905, briefed with creating a vessel that could be employed on an enemy's coastline, the Admiralty took several technological leaps forward to match Germany's own revolutionary vessels. Written by an influential expert in the field and covering all classes of submarine developed and deployed during the war, this book includes great technical detail, gripping operational accounts and is accompanied by artwork. With fascinating details of daring submarine raids in the Baltic and the Dardanelles, this book reveals the exceedingly dangerous world of early submarine warfare which claimed an extraordinary number of lives on both sides and paved the way for a new kind of naval warfare in the 20th century and beyond.