Bjørgvin-class coastal defence ship

The Bjørgvin-class coastal battleships were ordered by Norway in 1912 to supplement the older Eidsvold-class coastal defence ship and Tordenskjold-class coastal defence ships. The two ships laid down were compulsorily purchased by the Royal Navy when World War I broke out, and classified as monitors. The British government paid Norway £370,000 as compensation for each ship.

Ships in class

 * HNOMS Bjørgvin (1912) - Compulsorily purchased by the British Navy and renamed HMS Glatton (1914), blew up in a September 1918 accident.
 * HNOMS Nidaros (1912) - Compulsorily purchased by the British Navy and renamed HMS Gorgon (1914).

Description
The Bjørgvin class would be significantly more heavily armed than the previous Eidsvold class: In addition to the heavier armament, the two ships of the Bjørgvin class were also significantly better armoured, with her armour better distributed:
 * Two 24 cm/50 guns, which in British service were relined to use standard British ammunition and became 9.2"/51. These were considered among the longest-ranged guns in the world in 1918. As designed, they would have fired a 190 kg projectile with a muzzle velocity of 884 m/s (2,900 ft/s), capable of penetrating 22.2 cm of face-hardened armour at a range of 7,000 m.
 * Four 15 cm/50 in single turrets - one aft, one fore, two midships (one on either side). In British service they were relined to take standard 6 in ammunition.
 * Six 10 cm guns.
 * Two submerged torpedo tubes.
 * 7 in thick armour in the belt
 * 8 in thick armour on the turrets
 * 8 in thick armour in the barbettes
 * 2.5 in thick armoured deck
 * 8 in thick armour on the conning tower
 * 4 in thick armoured bulkheads