In 1917 Horton was awarded bar to his DSO for long and arduous services in command of overseas submarines, three years later as a captain he was awarded a second bar to his DSO for distinguished service in command of the Baltic submarine flotilla.
Horton rather famously moved his headquarters from Aberdour where he was under the thumb of the fleet commanders at Scapa Flow to Northways in north London, officially because he wanted a freer hand in running his command, but purportedly because Northways was located near some of his favorite golf courses.
Horton, an avid golfer, is said to have played a round of golf almost every day during the war, and was generously handicapped at a "financial 8".
For these achievements Horton was awarded the D.S.O. and on 31st December 1914, at the age of 31, promoted to Commander.
Aloof and sparing with praise, Horton, with great efficiency, used the growing resources available to him in the form of vastly increased numbers of efficient escorts around the convoys themselves, freely roaming Support Groups and "Hunter-Killer" groups formed around the small escort-carriers.
The greatly improved materiel which Horton's Command received from "Bletchly Park", the code-breaking centre reading a large part of the high security German "Enigma" traffic, very often enabled the staff ashore to redirect the convoys around the massive concentrations of U-boats set up by "Befehlshaber der Unterseeboote".