The history of the development of submarines covered in this book spans the most tumultuous years of the 20th century. When the little Holland No. 1 was launched in 1901, few could guess that the submarine would become the most potent weapon of war ever developed. British submarines were to play crucial roles in both world wars, protecting vital sea-lanes and destroying enemy shipping all over the world. From a petrol powered submersible, Britain went on to develop the submarine concept into some of the most remarkable of all submarine designs including the classic E-Class, ill-starred steam-powered K-Class, M-Class submarine monitor, and mighty T-Class of World War II. This encyclopaedia charts the history of every class of boat in service over the first 54 pioneering years. Each class of submarine is treated to its own profile charting its development and history in service, including the many differing sub-classes developed. The fate of each individual submarine is shown too.