He held that position until February 1919[1] when the post holder was renamed Chief of the Submarine Service.

[4] Roskill writes that the effective naval strength of the British Empire on the outbreak of war included 38 submarines.

[4] During the war the major operating arenas were the Norwegian waters; the Mediterranean where the Tenth Submarine Flotilla fought a successful battle against the Axis replenishment route to North Africa; and the Far East where Royal Navy submarines disrupted Japanese shipping operating in the Malacca Straits.

Horton's biographer, Rear Admiral William S. Chalmers, cites the opinion that a new regulation, which required the post holder to be an officer who had served aboard submarines in the Great War, was forced through for the sole purpose of ensuring that Horton was on a very short list of qualifiers for this post, almost ensuring his rapid transfer to Aberdour, so great was the desire of some within the Admiralty to have Horton revitalize the submarine arm.

[11] As of December 2020, official Royal Navy Freedom of Information responses said that "the combined 2* Rear Admiral post of Assistant Chief of the Naval Staff (ACNS) (Submarines)(SM), Flag Officer Scotland and Northern Ireland (FOSNI) and Rear Admiral Submarines has been disestablished.