Horton played a considerable role in developing British submarine doctrine before World War I. On 13 September 1914, he became the first British submarine commander to sink an enemy ship when E-9 torpedoed the German cruiser Hela near Helgoland. In October, he and Lieutenant Commander Noel F. Laurence took their submarines into the Baltic, where they operated successfully from Russian bases against ships carrying iron ore from Sweden to Germany. After his return in December 1915, Horton commanded submarines in the North Sea before taking over a submarine flotilla in 1919.
Promoted to captain in 1920, Horton acquired a reputation for ruthless efficiency as he took up increasingly senior posts. In 1932 he won promotion to rear admiral; in 1936 he was a vice admiral and took command of the Mediterranean Fleet's 1st Cruiser Squadron during the Spanish Civil War.
In 1938, Horton led the Northern Patrol, which was charged after the start of World War II with sealing the northern exit from the North Sea. He was then flag officer, submarines from January 1940 until November 1942. Horton directed submarine operations during the Norwegian Campaign and deployed his forces in the Atlantic Ocean and the Arctic Ocean and North Sea to assist the blockade of Germany. After Italy joined the war, he provided maximum possible support to British Mediterranean submarine forces in their assault on Italian and German supply lines to North Africa, operations that played a crucial role in the ultimate defeat of Axis forces there.
In November 1942, Horton became commander of the Western Approaches leading the fight against German submarines that resulted in their defeat in the Battle of the Atlantic. Horton benefited greatly from the valuable work of his precursor, Sir Percy Noble. He efficiently integrated and deployed his growing forces of well-trained convoy escorts, roaming support groups, and hunter-killer groups centered on escort carriers, all supported by shore-based very-long-range aircraft. Technological advances in radar, high-frequency direction finding (HF/DF), and antisubmarine weaponry increased his forces' effectiveness, while ultra intelligence from Enigma decryptions greatly aided both offensive and defensive strategic deployments.
Admiral Horton voluntarily retired in August 1945. He died in London on 30 July 1951.
Paul E. Fontenoy
Blair, Clay. Hitler's U-Boat War. 2 vols. New York: Random House, 1996, 1998.; Chalmers, W. S. Max Horton and the Western Approaches. London: Hodder and Stoughton, 1957.