A study of the history of mine warfare at sea from the earliest days to the present time, this work should be of interest to military lawyers and to all those concerned with the conduct and control of warfare. At the technical level, it is intended for laymen. While there is a chapter dealing with many technical matters relating to both mine warfare at sea and mine countermeasures, the sole purpose of that chapter is to give the non-technician, whether naval officer or civilian, a basic understanding of various categories of sea mines and their accessories and of mine countermeasure gear. It assumes that, like the author, the reader will have a minimum of electrical and mechanical knowledge. However, it is believed that after finishing this volume the reader will have a better understanding of the part that mines have played in warfare at sea in past conflicts as well as the part they may be expected to play in any future conflict.