Warships, and submarines in particular, have always been the subject of considerable interest to both the general public and the warship enthusiast, and every year books appear covering the many aspects of their development and operation both during and between the wars. However, the purpose of this book, and indeed of the whole series, as the title suggests, is to look at the subject in greater depth, to trace the development of the design, and to detail the armament and machinery they contained. The A class were the only ocean-going class of British submarine designed during the last war and although completed too late to actually see any action, they embodied all of the developments made in British submarine design during the final years of conflict. There is little doubt that had the war continued longer they would have given excellent service in the waters for which they were designed. In fact, in the years following the war many of the class operated comfortably in both tropical and arctic waters, establishing new records for both surface and submerged endurance. To illustrate this, in 1953 HMS Andrew carried out the first ever submerged crossing of the Atlantic; and earlier, in 1947, Alliance spent a record 30 days submerged off the coast of Africa.