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

Formed on 1 May 1912 from the 4th Division of the Home Fleet, its elderly ships were ordinarily only manned by a small maintenance crew during peacetime, but were intended to be manned by naval reservists when mobilised.

[1] It was conducting a test mobilisation in July 1914 as tensions increased between Great Britain and Imperial Germany[2] and was only partially demobilised before full mobilisation was ordered on 2 August.

At this time it consisted of the 7th and 8th Battle Squadrons of pre-dreadnought battleships and five squadrons of cruisers.

[3]