Arethusa class light cruisers

The Arethusa class of light cruisers marked a shift in the design of British light cruisers. They were smaller but faster than the various series of Town class cruisers, and were designed to operate with the destroyer flotillas. A Cruiser Committee, set up by Winston Churchill in 1911, had examined the problem posed by the increased speed of destroyers, which made the earlier scout class cruisers effectively obsolete in their original role. Given a choice between a fast enlarged destroyer or a somewhat slower armoured cruiser they had decided in favour of the cruisers. The new ships were described as “light armoured cruisers”.

The biggest problem with the new design was its mixed armament of 6in and 4in guns. The 4in guns were unreliable, and suffered from the same problems that dogged mixed gun armament on other ship types – two types of ammunition had to be carried and accurate gunnery was made more difficult by the different in the behaviour of the two sets of guns.

The Arethusa class cruisers and their successors were well designed for the needs of the First World War navy – they performed well in the North Sea – but all seven surviving ships were sold off during the 1920s when the navy once again needed cruisers capable of serving on overseas stations. Eight were ordered, with the first two entering service in August 1914, just as the First World War broke out.  

Commodore Reginald Tyrwhitt (1870-1951)
Reginald Tyrwhitt

During 1915 four of the Arethusa class cruisers were given a runway carried over the forecastle, making them the first Royal Navy cruisers to carry an aircraft, in this case a French monoplane. Intended as an anti-Zeppelin weapon, this aircraft was not a success and the platforms were removed in August 1915. As technology improved, an increasing number of British ships were equipped to carry aircraft, and in 1918 all seven surviving ships were given a new flying off platform, this time over the forward 6in gun. Four were also equipped to carry a kite balloon, used to spot U-boats.

These ships were subjected to a variety of wartime modifications. All had their 3pdr AA gun replaced with a 3in gun. In 1917 five of the surviving seven ships were given a second 3in AA gun, while Penelope and Undaunted were given a 4in AA gun. All seven ships were given two more 21in torpedo tubes during 1917. In 1917-18 all seven ships were given tripod masts and director fire equipment, and all but Undaunted were converted to carry mines, although not all did so in practise. 

Five of the Arethusa class cruisers served with the Harwich Force for all or part of the war, which the rest served with the Grand Fleet. Arethusa herself served as the flagship of Commodore Tyrwhitt, commander of the Harwich Force, until her sinking in 1916. Phaeton was the only member of the class to serve on an overseas station during the First World War, spending part of 1915 off the Dardanelles.

Displacement (loaded)


Top Speed


Armour – deck


 - belt





Two 6in Mk XII guns
Six 4in quick firing Mk IV guns
One 3pdr anti-aircraft gun
Four 21in torpedo tubes above water

Crew complement






Ships in class

HMS Arethusa
HMS Aurora
HMS Galatea
HMS Inconstant
HMS Penelope
HMS Phaeton
HMS Royalist
HMS Undaunted

Books on the First World War | Subject Index: First World War

How to cite this article: Rickard, J (20 October 2007), Arethusa class light cruisers ,

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