HMS Orion (1910)

HMS Orion was a dreadnought battleship of the Royal Navy. Launched in 1910, she was the lead ship of her class; she was the first so-called "super-dreadnought", being the first British dreadnought to mount guns of calibre greater than twelve inches, and the first British dreadnought to have all of its main armament mounted on the centreline.

Origin
Orion and her sisters were laid down at a time when the British Liberal Government was pledged by their election manifesto to reduce the scale of spending on armaments. Information from Naval Attachés in Germany produced information suggesting that Germany was building dreadnoughts at a rate which, if not countered, would lead to the German battle fleet approaching the size of the British. At that time there was in existence a policy known as the "two power standard", which called for the British battle-fleet to be at all times at least ten percent stronger than the two next strongest naval powers. The German plans as reported to the Government were seen as clearly breaching this policy. The First Lord of the Admiralty, Reginald McKenna, was therefore able to force his plans for the Orion-class dreadnoughts through Parliament; with the support of the Prime Minister, H.H. Asquith, and over the objections of David Lloyd-George and Winston Churchill.

Design and Appearance
Orion was the first British dreadnought, and with the exceptions of the American South Carolina and Michigan, the first anywhere to mount all of her main armament on the centre-line; the decision on disposition of the turrets preceded the decision on the calibre to be employed. It was known that Germany was producing large numbers of naval gun barrels of eleven and twelve inches in calibre; as the British 12-inch 50-calibre gun had reached the end of its development life it was felt necessary to increase the size of the guns of the main armament to 13.5 inches. This in turn led to a significant increase in the size of the ship, as compared to previous dreadnoughts, and an increase in displacement of some 2,500 tons.

The foremast was positioned immediately aft of the fore-funnel, as had been the case in Dreadnought but which had not been the case in the Bellerophon class or the St. Vincent classes, although it had been aft of the fore-funnel in the Colossus class. This led, as in earlier ships with the same disposition, to the control top being rendered virtually uninhabitable by smoke and hot funnel exhaust when steaming into wind. The only reason that can be found for this arrangement is to provide a convenient place to affix the booms to handle the ship's boats.

The height of the topmast was reduced and torpedo nets removed in 1915; the fire control platforms on the foremast were extended after Jutland, and an aeroplane platform was added to the roof of "B" turret.

Armament
The main armament was ten 13.5 inch (343 mm) 45-calibre Mark V guns, disposed in five double turrets all positioned on the centre-line of the ship. "A" turret was positioned on the forecastle deck, and had an uninterrupted arc of fire over the deck of some 300 degrees. "B" turret was placed immediately aft of "A", one deck higher. In theory the arc of fire of "B" turret was also 300 degrees; in practice, because of the insistence by the Admiralty of the retention of sighting hoods in turret roofs, firing over "A" turret caused intolerable blast effects in "A" turret, limiting "B" therefore to firing on broadside arcs only. "Q" turret, positioned between the after funnel and the after superstructure and one deck level lower than "A", had an arc of fire of 120 degrees on either beam, with no possibility of fire either ahead or astern. "X" turret was at the same deck level as "A" turret; positioned on the quarterdeck and superfiring over "Y" turret, it possessed a theoretical arc of fire of 300 degrees over the stern, but in practice suffered from the same limitation as did "B" turret in terms of firing over the lower turret. "Y" turret was placed on the quarterdeck at the same height as "Q" turret, and enjoyed an uninterrupted arc of fire over the stern of 300 degrees. Maximum ammunition stowage was one hundred rounds per gun.

Sixteen four-inch (102 mm) 50-calibre Mark VII breech-loading guns were shipped as secondary armament. They were disposed symmetrically, eight being in the forward superstructure with fields of fire forward and on the beam, and eight being in the after superstructure and firing on the beam and aft. The number of guns was reduced to thirteen during the war, and a 4-inch anti-aircraft gun was installed on the quarterdeck.

Four 3-pounder saluting guns were carried high in the superstructure.

There were three 21-inch (533 mm) underwater torpedo tubes; one on each beam and one discharging astern. A total of twenty torpedoes was carried.

Armour
At the time of the design of Orion, the largest calibre of gun carried by battleships of other nations was twelve inches. It was believed, however, that as part of the continuing trend to increasing size in this class of warship, calibres would inevitably rise. Orion and her sisters therefore received heavier and more extensive armour than had been carried by earlier British dreadnoughts.

The main waterline belt was twelve inches thick, and extended from a point level with the centre of "A" barbette to a point level with the centre of "Y" barbette. The lower edge was three feet four inches below the waterline at normal displacement. Above this belt was an upper belt of eight inches in thickness, which ran for the same length. The belt extended further upwards than in previous dreadnoughts; the upper edge was at the level of the middle deck, giving a total belt height of twenty feet six inches. Forward of "A" barbette the belt was extended by a short length of armour of six inches in thickness tapering to four; and the after end of the belt continued as a short strake two and a half inches thick. The extreme ends of the ships sides were not armoured.

A torpedo defence screen ran from "A" barbette to "Y" barbette, and extended from the lower deck to the bottom of the ship. It was of varying thickness, from one to one and three quarter inches, and was intended to prevent mine or torpedo detonation from causing magazine explosion.

An armoured bulkhead ten inches thick ran from the after end of the armour belt around "Y" barbette, and there was a further bulkhead mid-way between this barbette and the stern composed of two and a half inch armour. Both bulkheads extended from lower deck to upper deck level. The forward bulkhead, which ran from the forward end of the main belt on either beam to the forward aspect of "A" barbette, was eight inches thick between the forecastle deck and maindeck levels, and six inches thick from maindeck to lower deck. A further bulkhead of four inches thickness was situated in the bow, one third of the distance from the stem to the forward barbette.

There were four armoured decks. The upper and main decks were of one and a half inch armour, the middle deck was one inch thick, and the lower deck was two and a half inches tapering to one inch forward, and four inches tapering to three aft. The greater thickness was over the magazines and machinery.

The faces of the main armament turrets were eleven inches thick, the turret crowns being four inches tapering to three. The barbettes were ten inches thick at their maximum, tapering to seven, five or three inches in areas where adjacent armoured structures or armoured decks afforded some protection.

The conning tower was protected by eleven inches of armour, tapering to three in less vulnerable areas.

Machinery
Four Parsons turbines drove four screws, and were provided with steam by eighteen Babcock and Wilcox boilers. The designed shaft horse power (SHP) was 27,000 and the design maximum speed was 21 knots. Normal fuel load was 900 tons, but up to 3,300 tons could be stowed, together with 800 tons of fuel oil. Radius of action was 6,730 nmi at ten knots, or 4,110 nmi at nineteen knots. In her trials on completion she achieved 29,108 SHP, which produced a measured speed of 21.02 knots; her best measured speed was 22.3 knots.

Career
Orion was laid down in Portsmouth Dockyard on 29 November 1909. She was launched on 20 August 1910, ran her sea trials starting in September 1911 and was commissioned on 2 January 1912. She joined the second division of the Home Fleet as second flag-ship, in which role she relieved the pre-dreadnought battleship Hibernia. On 7 January 1912 she was damaged when Revenge broke loose from her moorings and collided with Orion, causing minor damage to the port side.

At Jutland on 31 May 1916 she carried the flag of Rear-Admiral Arthur Leveson, the second in command of the 2nd Battle Squadron of the Grand Fleet. She took part in the general battleship action, claiming no hits and receiving none. In the later part of the action she claimed four hits on the German battlecruiser Lützow. As this battlecruiser did not survive the action confirmation was not possible.

She remained with the Grand Fleet, seeing, in common with the rest of the battle-fleet, no more action during the remainder of the war. On 3 October 1919 she became flagship of the Reserve Fleet at Portsmouth, and in June 1921 she became a seagoing gunnery training ship at Portland.

On 12 April 1922 she was paid off onto the disposal list under the terms of the Washington Treaty. On 19 December she was sold to shipbreakers Cox and Danks, and from February 1923 she was broken up at Upnor.