BL 6-inch Mk XI naval gun
# BL 6-inch Mk XI naval gun

The BL 6-inch Mark XI naval gun was a British 50 calibres high-velocity naval gun which was mounted as primary armament on cruisers and secondary armament on pre-dreadnought battleships from 1906 onwards.

## History

The gun with its increased length of 50 calibres gave improved firepower over the current 6-inch Mk VII gun of 45 calibres. However, its increased length and weight made it unwieldy in the current manually operated shipboard mountings on light cruisers, which did not provide a steady platform. Britain reverted to 45-calibres guns in new warships from 1914 onwards with the BL 6-inch Mk XII gun. Of the 177 produced 126 remained for Royal Navy use in 1939.

## Naval gun

Guns were mounted in the following ships :

* The last three King Edward VII-class battleships Britannia, Africa and Hibernia laid down 1902–1904
* Armoured cruisers: HMS Duke of Edinburgh and Black Prince laid down 1903
* Bristol-class light cruisers laid down 1909
* Weymouth-class cruisers laid down 1910
* Chatham-class light cruisers laid down 1911
* Birmingham-class light cruisers laid down 1912
* Monitor HMS Marshal Ney as re-gunned in 1918

## Coast defence gun

The Mk XI gun was emplaced for coast defence in South Africa and particularly in Australia leading up to World War II, and remained in service until the 1950s. Guns in Australia came from the decommissioned World War I cruisers HMAS Sydney, HMAS Melbourne and HMAS Brisbane and were emplaced in northern Australia and Torres Strait to defend against possible attack by Japan, and on Rottnest Island WA, Brisbane and the Sydney harbour and Port Kembla defences.

