As a young officer, John Locke Marx grew up in the hey day of the Old Navy, with its gun boats, naval brigades and autonomous captains ruling distant seas; he was a mature officer in the New Navy, with its armed cruisers and battleships, its great Atlantic Fleet and its professional Officer Corps; he was a retired Admiral in the First World War, fighting as a captain in the dangerous Q ships and as an active admiral in charge of convoys when it ended. Thus his career spanned the long and important development of the Royal Navy from 1866-1917, from the Pax Britannica to Jutland. Admiral Marx left an archive of diaries, letters and papers, important not only for its historical interest and its intrinsic readability, but for the light it throws on Marx's distinctive personality and the way in which the experience of a naval officer impacted upon it. Every page of his journal was headed private, and there is no doubt that he intended it for his eyes alone. In his sexual and social experiences, his imperial adventures, and his World War One heroism, his papers present a unique account of "A Naval Life".