|Name||No||Yard No||Builder||Laid down||Launched||Comp||Fate|
|Erebus (ex-M34)||M02, I02||492||Harland & Wolff, Govan||12.10.1915||19.6.1916||9.1916||sold for BU 7.1946|
|Terror (ex-M35)||M5A, I03||493||Harland & Wolff, Belfast||26.10.1915||18.5.1916||8.1916||sunk 24.10.1941|
|Displacement normal, t||8000|
|Displacement full, t||
|No of shafts||
2 4-cyl. VTE, 4 Babcock & Wilcox boilers
|Power, h. p.||
|Max speed, kts||
|Fuel, t||784 oil|
inner belt: 102, bulkheads: 102, barbette: 203, turret: 330 (face), deck: 51 - 25 (102 over magazines)
1 x 2 - 381/42 BL Mk I, 2 x 1 - 152/40 QF Mk II, 2 x 1 - 76/50 12pdr 18cwt QF Mk I, 1 x 1 - 76/45 20cwt QF Mk I, 4 x 1 - 7.7/87
The urgent need for heavy bombardment ships lo replace battleships in the Dardanelles led to an order being placed for four 381mm-gunned monitors in May 1915 to supplement the Marshal Ney class. Designated M34-37, they were to be built by Harland & Wolff (M34, 35), Swan Hunter (M36) and Hamilton (M37) and turrets were to be reallocated from the battleship Royal Oak. The new Balfour-Jackson Admiralty Board reviewed priorities early in June 1915 and decided that the battleship program could not be delayed, and so the four monitors were cancelled on 10 June. Then in August 1915 came the bad news oft he Marshal Ney`s trials, and consideration was given to putting both the Marshals` turrets into new monitors. The outcome of this convoluted process was the first opportunity to incorporate lessons from the earlier monitors. At last sufficient power was stipulated to make a minimum of 10kts, and at 6000hp this was more than twice the previous figure. The hull was made appreciably longer to accommodate the machinery but above all it secured a reasonably fine entrance and run (50° angle of entrance as compared with 120° in the 356mm and 305mm monitors). The hull aided propulsive efficiency and improved steering as well. The basic hull had the same beam as Marshals but the 'bulge' was narrower and filled with crushing tubes to improve resistance to explosions. It proved impossible to restrict draught to 3.0m but even 3.4m was a small penalty to pay for all the other improvements in design. A proper bridge was provided and the funnel was tall enough and far enough back from the bridge to avoid smoke interference. Harland & Wolff`s Govan vard had already started work on M34, and material assembled for her and M35 was used wherever possible, particularly 102mm armour. To speed construction Marshal Ney`s 381mm turret was transferred to Terror, but as the Admiralty had now decided to retain Marshal Soult her turret was no longer available. Fortunately two spare turrets had been earmarked for Furious in case her 457mm guns proved unsatisfactory, and one of these was brought forward for Erebus. After all the disappointments with previous monitors the machinery trials proved a great success: Terror made 13kts instead of the 12kts expected, and Erebus averaged 14kts. Both ships could make 12kts in service.
There were bulges intended for underwater protection. The citadel was consisted of 102mm inner belt, 102mm bulkheads and armoured deck (102mm over magazine and 51-25mm over machinery).
about 1916, Terror: received 2 x 1 - 152/40 QF Mk II designed guns (completed without these guns)
late 1917, both: + 2 x 1 - 152/40 QF Mk II
summer 1918, both: - 4 x 1 - 152/40; + 8 x 1 - 102/44 BL Mk IX
late 1918, both: + 1 x 1 - 76/45 20cwt QF Mk I, 2 x 1 - 40/39 2pdr QF Mk II
1939 - 1940, Terror: - 8 x 1 - 102/45, 2 x 1 - 76/50, 2 x 1 - 40/39; + 6 x 1 - 102/45 QF Mk V, 2 x 4 - 12.7/62
1939 - 1940, Erebus: - 8 x 1 - 102/45, 2 x 1 - 76/50, 2 x 1 - 40/39; + 6 x 1 - 102/45 QF Mk V, 4 x 4 - 12.7/62, 2 x 20 - 178 UP rockets projectors
1940, both: main deck thickness over machinery increased to 102mm, aft lower deck thickness increased from 25 up to 64 - 51mm
early 1941, Terror: + 7 x 1 - 20/65 Breda M1939, full displacement: 9400t
1941, Erebus: + 1 x 20 - 178 UP rockets projector, 2x type 285 radars
1943, Erebus: - 3 x 20 - 178 UP, 4 x 4 - 12.7/62; + 3 x 4 - 40/39 2pdr QF Mk VIII, 1 x 1 - 40/39 2pdr QF Mk II, 7 x 1 - 20/70 Oerlikon Mk II/IV
1943-1944, Erebus: presumably + type 276, type 279B, 2x type 282 radars
1943 - 1944, Erebus: + 8 x 1 - 20/70 Oerlikon Mk II/IV, fuel storage decreased to 90t, full displacement increased to 9800t
1/1946, Erebus: 1 x 2 - 381/42 Mk I, 6 x 1 - 102/45 HA Mk III, 2 x 1 - 76/45 Mk IV, 3 x 4 - 40/39 Mk VII, 1 x 1 - 40/39 Mk VIII, 15 x 1 - 20/70 Mk III, type 276, type 279B, 2x type 282, 2x type 285 radars
Erebus 28.10.1917 was hit by German distance-controlled explosive boat FL12. 700kg charge detonated on the bulge, blowing a 15m hole in it but doing very little damage to the hull; ship was back in service 21.11.1917. Terror was used as Director and Fire Control TS since January 1919, served as turret drillship since May 1924 till WWII. Terror was badly damaged by nearly bomb hits from German Ju 87 aircraft 22.2.1941 and sunk two days after near Libyan coast.
Many thanks to Wolfgang Stöhr for additional information on this page.