The Second Fleet was a reserve formation of the Royal Navy that briefly existed before the First World War.

Formed on 1 May 1912 from the Third Division of the Home Fleet, its ships were manned by a nucleus crew during peacetime, but were intended to be manned by men from the naval schools when mobilised.

[1] It reported directly to the Commander-in-Chief, Home Fleets.

The fleet was mobilised in late July 1914 as tensions increased between Great Britain and Imperial Germany and remained on active duty until war was declared on 4 August.

[2] It reformed the Channel Fleet upon the declaration of war and consisted of the Fifth and Sixth Battle Squadrons, equipped with a total of 15 pre-dreadnought battleships and the majority of the Home Defence Patrol Flotillas.