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Feature Extract: Weapons of War: Leander-class Cruiser

Photo: HMAS Sydney in 1936. The Australian Leanders had two funnels, giving them a distinctive look. (State Library of Victoria)

 

The first class of British light cruisers built under the terms of the 1930 London Conference, the Leander-class had a reputation for ruggedness, good seakeeping, and speed.

Seeing action in every theatre of the Second World War, the eight British-built Leander-class cruisers were an essential part of the Royal Navy’s maritime power but are often overlooked in favour of newer ships. The class also provided the Royal Australian Navy with the bulk of it major surface units and the fledgling Royal New Zealand Navy its first two major warships.

While largely supplanted by newer classes, five Leanders still remained in Royal Navy hands until 1941. Each was named after a figure from Greek or Roman mythology, except the three destined for Australia, instead named after Australian towns and cities.

DESIGN

Originally, more Leander-class ships were planned. However, the general displacement limit set by the arms-limiting London Conference meant the Royal Navy had just 91,000 tons of total cruiser displacement remaining. The Leander’s were heavy ships, and this resulted a revision down to eight vessels. However, being ‘light’, or 6in gun, cruisers, the enforcement of such limits was less strict when compared to the County-class ‘heavy’ 8in gun cruisers. Therefore, most of class were overweight and Leander herself displaced 1,000 tons more than planned.

Built with speed and ocean-going endurance in mind, the design adhered to the traditional principles of the cruiser in protecting trade routes. With their main opponents likely to be auxiliary cruisers – which notionally would always be outgunned – armament and protection were secondary concerns, this continued to be the case with successor to the Leander’s, the Arethusa-class, which took this notion of contented superiority further.

Each ship carried a catapult (but no hangars) for a spotter aircraft, normally a Fairey Seafox or Supermarine Walrus. The first of the class to enter service was Leander, commissioned in March 1933 after a two-and-a-half-year build.

The 6in guns of Orion bombard targets on the River Garlgliano, Italy, in support of 5th Army.

Despite their size and weight, the ‘Leander Group’ exceeded expectations in regard to speed. Six boilers turned steam turbines on four shafts, producing some 72,000shp. In a first for British cruisers, these ships had propulsion machinery and boilers arranged together and sharing a single funnel, giving the Leander’s their distinctive appearance.

The system worked well, being reliable and powerful. On trials, Leander exceeded 32kts at standard load, and her maximum speed only slightly dropped at full load – almost 2,500 tons heavier. However, a single penetrating hit amidships could knock out the entire propulsion and while fast, a limitation was range. Although the ships were relatively large, their compact design left little room for fuel and while their 5,700nmi range compared well against similar German and Italian ships, they were short-ranged next to comparable French and American cruisers. Like the British, the French had a global empire, and the Americans were an ocean away from any major conflict. Operational reach was a vital consideration and in this the Leander’s fell short.

The three Australian ships of the ‘Amphion’ – or Modified-Leander – Group were slightly longer, displaced less, and had two fewer boilers. Yet maximum speed was only marginally affected. As the Australian vessels featured separated propulsion machinery, they differed visually in that they were built with two funnels.

SHIPS OF THE LEANDER-CLASS
Name / Pennant No.: Commissioned: Fate:
Leander Group
Leander / 75 24 March 1933 To RNZN 1941-1945, broken up 1950.
Orion / 85 18 January 1934 Broken up 1949.
Neptune / 20 23 February 1934 Sunk by mines off Tripoli, Libya, 19 December 1941.
Ajax / 22 12 April 1935 Broken up 1949.
Achilles /70 10 October 1933 To RNZN 1941-1946, sold to India as INS Delhi 1948, broken up 1978.
Modified Leander/Amphion Group
Amphion / 29 15 June 1936 Sold to RAN as HMAS Perth in 1939, sunk during the Battle of Sunda Strait on 1 March 1942.
Apollo / 63 13 January 1936 Sold to RAN as HMAS Hobart in 1938, broken up 1962.
Sydney / 48 24 September 1935 Originally Phaeton, renamed on launch. Lost in mutually destructive surface action with Kormoran on 19 November 1941.


ARMAMENT

The Leander-class was armed with eight BL 6in Mk.XXIII guns. These were more powerful than the guns arming earlier conventional cruisers and with the last British heavy cruiser completed in 1931, the Mk.XXIII became the standard armament for Royal Navy cruisers (excepting anti-aircraft cruisers) until introduction of the Tiger-class.

The guns were housed in four Mk.XXI turrets – two fore and a pair aft. Elevation was +60° to -5° and rate of fire (depending on elevation, crew training and fatigue) was a respectable eight rounds per gun per minute (rpgpm). Loading consisted of the projectile and separate bagged charges, and the barrels had to be lowered below 12.5° to be reloaded. Theoretical maximum range was 25,500yds (23,300m) with 45° elevation – though in practice 24,800yds (22,500m) was more achievable – and with an initial muzzle velocity of 2,760fps (840m/s) the 112lb (51kg) shells took more than 70 seconds to hit their target at maximum range.

An alternative to the main batteries for the 21in (553mm) Mk.IX torpedo was provided by two quadruple launchers, one each side, positioned amidships. Designed in 1928, the Mk.IX was used primarily on British light cruisers and replaced the older Mk.VII on some County-class cruisers.

Secondary armament consisted of four QF 4in Mk.V guns in high-angle mountings that doubled as the primary anti-aircraft weapons. These had a surface range of 16,300 yards and an anti-aircraft ceiling of 28,750ft. These were replaced by QF 4in Mk.XVI guns in twin mounts. These could hit aircraft at up to 39,000ft and surface targets out to 19,850 yards and had a greater rate of fire – around 20 rpgrm. Each ship in the class received these by 1938, except Achilles which only received hers in mid-1943, and Sydney.

PROTECTION

The Leander-class were lightly armoured. Less strict enforcement of displacement limits did mean that protection was not necessarily a sacrificial concern, but the liberal application of plate would reduce speed and sea-keeping. It was largely impossible to armour light cruisers against guns of eight inches or greater – threats that theoretically should be outrun or outmanoeuvred. As such, the ships were protected well enough to defend against six-inch shells fired at mid/long range.

The Leander Group featured up to three inches of armour around the magazines, behind a protective belt some four inches thick that also encompassed machinery spaces and boilers. The deck was protected by one-and-a-quarter inches of plating – up to two inches in places – with an additional one-and-a-quarter inches above the magazines. The turret fronts were an inch thick, while sloped plating one-and-a-quarter inches thick protected steering gear.

Because the three vessels modified to Australian requirements split the machinery spaces into separated compartments, those ships required the armour to cover a greater area.

Although the armour was somewhat light, solid and rugged construction added to robustness of all eight ships. Speed was not compromised, and the ships were capable of sustaining major damage.

The torpedo damage to HMAS Hobart, demonstrating the ruggedness of the Leander-class vessels.

BATTLE OF THE RIVER PLATE

Such ruggedness would serve the class well in the first decisive naval action of the Second World War, one that would immortalise the Leander-class cruisers.

At the onset of hostilities, Achilles was patrolling off South America where she joined Ajax, which had sunk the German merchant Olinda on 3 September 1939, and with the heavy cruiser Cumberland intercepted the Carl Fritzen and Ussukuma.

Having sailed to the South Atlantic before the war, the German pocket battleship and commerce raider Admiral Graf Spee – able to outrun almost any vessel with the guns to sink her and outgunning almost any vessel capable of catching her – sunk nine British merchant ships in the Indian and South Atlantic oceans. Force G – Ajax, Achilles, Cumberland, and another heavy cruiser Exeter – under Commodore Henry Harwood, was one units tasked with finding her.

Anticipating Graf Spee would move to the River Plate, Harwood steamed there and practiced the tactics he devised for attacking a pocket battleship. In daylight, this involved splitting and engaging from multiple sides. However, Cumberland was now undergoing refit in the Falklands and Harwood’s force was outgunned.

At 6.16am on 13 December, Exeter sighted the raider and attacked from the southwest. Ajax and Achilles went northwest. Graf Spee misidentified the British vessels, and underestimating her foe, gave up her range advantage and closed in, opening fire on Exeter at 6.18am. The British fired back but within five minutes, a salvo landed close to Exeter and splinters incapacitated her seaplane and torpedo crews. At 6.26pm Exeter took a shell on her ‘B’ turret, knocking it out, the shrapnel killing or wounding all on the bridge except for the captain and two others. Communications were down, and instructions were being passed down chains of sailors. While the Germans were accurate, so too were the British, but the Spee’s 11in shells were far more destructive.

Ajax and Achilles – both faster than Graf Spee – closed to 13,000yds, forcing her to split her fire. Exeter was hit again, losing her ‘A’ turret. She was on fire and severely damaged, but her ‘Y’ turret was still firing under local control – the gunnery officer stood on the roof shouting instructions. They scored a hit on Graf Spee’s fuel processing facilities, leaving her with just enough to get to South America.

This extract was formed from our ‘Weapons of War: Leander-class Cruiser’ feature. Read the rest of this exciting feature in the January issue of Britain at War – in the shops NOW!

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