View source for Diadem-class cruiser

{{Use dmy dates|date=September 2017}}
{{Use British English|date=September 2017}}
{|{{Infobox ship begin}}
{{Infobox ship image
|Ship image=HMCS Niobe LOC 08665.jpg
|Ship caption={{HMCS|Niobe}}
}}
{{Infobox ship class overview
|Name=''Diadem'' class
|Builders=
|Operators=*{{navy|United Kingdom}}
*{{naval|Canada|1911}}
|Class before={{sclass|Powerful|cruiser|4}}
|Class after={{sclass|Cressy|cruiser|4}}
|Subclasses=
|Cost=
|Built range=1896–1903
|In service range=   
|In commission range=1898–1925  
|Total ships building= 
|Total ships planned=
|Total ships completed=8
|Total ships cancelled=
|Total ships active=
|Total ships laid up=
|Total ships lost=
|Total ships retired=8
|Total ships preserved=
}}
{{Infobox ship characteristics
|Hide header=
|Header caption= 
|Ship type=[[Protected cruiser]]
|Ship displacement=11,000 tons<ref name=Con>Conway's, 1860–1905</ref><ref name="Janes1900"/>
|Ship length=*{{convert|435|ft|m|abbr=on|1}}
*({{convert|462|ft|6|in|m|abbr=on}} [[Length overall|o/a]])
|Ship beam={{convert|69|ft|m|abbr=on|1}}
|Ship height=
|Ship draught=*{{convert|25|ft|6|in|m|abbr=on}}
*{{convert|27|ft|6|in|m|abbr=on}}<ref name="Janes1900"/>
|Ship draft=
|Ship power=
|Ship propulsion=*2 shaft [[steam engine|triple expansion engines]]:
*{{convert|16,500|hp|kW|abbr=on}}
*(''Ariadne'', ''Spartiate'', ''Amphitrite'' and ''Argonaut'': {{convert|18,000|hp|kW|abbr=on}})
*[[Belleville boiler]]s
|Ship speed=*{{convert|20.25|kn}}
*(''Ariadne'', ''Spartiate'', ''Amphitrite'' and ''Argonaut'': {{convert|20.75|kn}})
|Ship range=*{{convert|2000|nmi|-2|abbr=on}} at {{convert|19|kn|1}}
*(bunker capacity 1900 tons)<ref name=Con/><ref name=Br>Brassey's (p.220-233) quotes a coal capacity of 1,000 tons.</ref>
|Ship endurance=
|Ship complement=677
|Ship sensors=
|Ship EW=
|Ship armament=
*16 × single [[Elswick 6 inch naval gun|QF {{convert|6|in|sigfig=3|adj=on}} guns]]<ref>Tony Di Giulian, [http://www.navweaps.com/Weapons/WNBR_6-40_mk1.htm British 6"/40 (15.2 cm) QF Marks I, II and III]</ref><ref group=note>''Jane{{'}}s Fighting Ships 1900'' claimed on page 108 that the ''Diadem''s had 6-in 45 calibre guns. The 6-in BL Mk VII was 45 calibres. This was later corrected in subsequent editions to the 40 calibre QF guns</ref>
*14 × single [[QF 12 pounder 12 cwt naval gun|12-pounder (76 mm) QF guns]]
*3 × single [[QF 3 pounder Hotchkiss|QF 3-pounder (47 mm) guns]]
*2 × [[British 18-inch torpedo|18-inch (450 mm)]] [[torpedo tube]]s (underwater)
*8 Maxim machine guns
|Ship armour=*[[Casemate]]s and gun shields {{convert|4.5|in|mm|abbr=on}}
*Hoists {{convert|2|in|mm|abbr=on}}
*[[Deck (ship)|Deck]] {{convert|4|-|2.5|in|mm|abbr=on}}
*[[Conning tower]] {{convert|12|in|mm|abbr=on}} fore 
*{{convert|6|in|mm|abbr=on}} tube to fore conning tower
*{{convert|2|in|mm|abbr=on}} aft conning tower
*Armour was Harvey Nickel steel, except for armoured deck.<ref name=Con/><ref name="Janes1900"/>
|Ship armor=
|Ship aircraft=
|Ship aircraft facilities=
|Ship notes=
}}
|}

The '''''Diadem''-class cruiser''' was a [[ship class|class]] of "first class" [[protected cruiser]] built for the [[Royal Navy]] during the 1890s that served in the [[First World War]]. The class consisted of eight ships, built at a cost of around £600,000 each.

They were considered "good sea boats" but criticised for their lack of a heavy calibre main armament, bulky unprotected sides, average speed and lack of manoeuvrability despite being considered large ships when completed. They were the last British first class protected cruisers; the [[armoured cruiser]] taking the large cruiser role in future."<ref name=diaww1>[http://www.worldwar1.co.uk/armoured-cruiser/hms-diadem.html Diadem class at worldwar1.co.uk]</ref>

== Design ==
[[File:HMS Diadem (1894) Plan and Elevation.JPG|thumb|left|{{center|Contemporary deck plan and port elevation of ''Diadem''-class cruiser}}]]
The ''Diadem''s were designed by [[William Henry White|Sir William White]], and are typical of British design practice of the period, with high freeboard (by the standards of the time) and the use of 'double-decker' casemates, with the hull forward and aft cut away to allow fore and aft fire from the casemate guns. [[Casemate]]s provided protection for the guns and allowed a large number of guns to bear on the broadside; however, the lower (main deck) guns were almost unusable in heavy seas.<ref name=b1>Brown, p. 136</ref>

According to a contemporary (1900) edition of Jane's Fighting Ships the hulls were wood sheathed and coppered.<ref name="Janes1900">Jane's Fighting Ships 1900, p.108</ref> and "There are coal bunkers on the lower deck, and above and below the armour deck. The pair of 6 in guns forward and aft are served by one hoist to the pair, each casemate has its own hoist: those to the double casemates being double. The machinery weighs 1630 tons: the boilers occupy a space of about 132 feet (40 m). Working pressure is [300 to 250 [[lbf/in²|psi]] (2.1 to 1.7 [[MPa]])].<ref name="Janes1900"/> "The ships are almost absolutely identical in appearance. The ''Diadem'' and ''Andromeda'' have no steam pipes abaft the first two funnels, while all the others have steam pipes before and abaft each funnel."<ref name="Janes1900"/>

== History ==
The ''Diadem'' class was intended, like the preceding {{sclass|Powerful|cruiser|4}}, for trade protection, and were intended to be "capable of dealing with any cruiser existing or building".<ref name=b1/> The ''Powerful''s had proved costly and demanding in manpower, and the new class had to represent a more economical solution, that could be built and operated in greater numbers. To achieve this, the specification was reduced relative to the ''Powerful''s: power and speed were reduced from {{convert|25,000|ihp|kW|lk=in}} ({{convert|22|kn|lk=in}}) to {{convert|16,500|ihp|kW|abbr=on}} (about {{convert|20|kn|abbr=on}}), the thickness of the protective deck reduced from {{convert|6|in|mm}} to {{convert|4|in|mm}}, and the armament simplified by replacing the single {{convert|9.2|in|mm|0|adj=on}} guns fore and aft with pairs of {{convert|6|in|mm|0|adj=on}} guns, mounted side by side.<ref name=con1>Conway's, 1860–1905, p. 68</ref> These changes saved about £100,000 per ship (approximately 15%) relative to the ''Powerful'' design.

With eight ships, each of 11,000 tons and costing £600,000, the ''Diadem''s were an important class. However, they proved controversial. The naval journalist [[Fred Jane]] characterised them as "much-discussed" and complained that "all the weak points of the ''Powerful''s were exaggerated in them".<ref>Jane, ''The British Battlefleet'', p. 284</ref> In particular, contemporary critics raised  objections to their indifferent speed, poor manoeuvrability, and lack of heavy guns, and the fact that, while most of the armament was well protected in casemates, the fore and aft pairs of guns, which commanded the greatest fields of fire, were protected only by gunshields.<ref name=diaww1/><ref name=con1/>

Although the powerplant used [[Belleville boiler]]s, which were of the then-new [[water-tube boiler|water-tube]] type, most of the ships enjoyed the reputation of good steamers; the exception was ''Niobe'', whose engines gave persistent trouble. The first four ships were troubled by vibration; to remedy this, the engine rooms of the last four were rearranged; the new configuration also provided a {{convert|1500|hp|abbr=on}} increase in power.<ref>Brown, ''op cit''</ref> All eight ships exceeded their design power on trials; the first four averaged {{convert|20.5|kn|km/h|1}} in service, the later four {{convert|21|kn|km/h|0}}.

In general the ''Diadem''s served most of their careers in home waters, although there were some deployments to [[China Station]], the [[Mediterranean]] and the [[Caribbean]]. ''Niobe'' was sold to [[Canada]] in 1910. After 1906, they were only occasionally in commission, and by 1914 the class had for the most part been relegated to training ship and depot ship duties. However, with the outbreak of the [[First World War]], several of them were reactivated, initially for patrol duties with the 9th Cruiser Squadron in the Eastern [[Atlantic]]. In 1917 ''Amphitrite'' and ''Ariadne'' were converted into [[minelayer]]s, for service with the [[Dover Patrol]]. ''Ariadne'' was the only war loss, being torpedoed by the German submarine {{ship|SM|UC-65||2}} on 26 July 1917. By the end of the war the survivors had again been withdrawn from active service, and all of them had been sold for scrap by 1932, with the exception of  ''Andromeda'', which served as a boys’ training ship until 1956.<ref>Conway's, 1906–1921, p. 10</ref>

== Building Programme ==
Standard British practice at that time was for building costs to '''exclude''' armament and stores.<ref group=note>[[Brassey's Naval Annual|Brassey's Naval Annual (BNA)]] gave costs for these ships that were on average £25,600 greater in the 1904 and 1905 editions than in the 1906 and subsequent editions. Brassey's Naval Annual 1914 (p. 200) only lists two of the ''Diadem''s and quotes the same cost as the 1906 edition. ''Niobe'' is listed under Canada (page 207) but no cost is given.</ref>

{| class="wikitable"
|-valign="top"
! width=120  rowspan=2 |Ship
! align = center  rowspan=2 | Builder<ref name=Con/>
! colspan = 3 |Date of
! colspan = 2 |Cost<small> according to</small>
|-valign="top"
! align = center width = 74 | Laid Down<ref name=Con/>
! align = center width = 74 | Launch<ref name=Con/>
! align = center width = 74 | Completion<ref name=Con/>
! align = center  | ([[Brassey's Naval Annual|BNA]] 1904 & 1905)<ref>Brassey's Naval Annual 1904, pp. 220–233</ref><ref>Brassey's Naval Annual 1905, pp. 242–249</ref>
! align = center   | (BNA 1906)<ref>Brassey's Naval Annual 1906, pp. 216–223</ref>
|-
| {{HMS|Diadem|1896|2}}
|align="center"|  [[Fairfield Shipping and Engineering|Fairfield]], [[Govan]]
|align=right   |  23 Jan 1896
|align=right   |  21 Oct 1896
|align=right   |  19 July 1898
|align="center"|  £582,662
|align="center"|  £554,863
|-
| {{HMS|Amphitrite|1898|2}}
|align="center"|  Vickers, Barrow
|align=right   |  8 Dec 1896
|align=right   |  5 Jul 1898
|align=right   |  17 Sep 1901
|align="center"|  £575,300
|align="center"|  £552,795
|-
| {{HMS|Andromeda|1897|2}}
|align="center"|  [[Pembroke Dockyard]]
|align=right   |  2 Dec 1895
|align=right   |  30 Apr 1897
|align=right   |  5 Sep 1899
|align="center"|  £601,356
|align="center"|  £574,916
|-
| {{HMS|Argonaut|1898|2}}
|align="center"|  [[Fairfield Shipping and Engineering|Fairfield]], [[Govan]]
|align=right   |  23 Nov 1896
|align=right   |  24 Jan 1898
|align=right   |  19 Apr 1900
|align="center"| £573,704
|align="center"|  £545,756
|-
| {{HMS|Ariadne|1898|2}}
|align="center"|  [[John Brown & Company|J&G Thompson]], [[Clydebank]]
|align=right   |  29 Oct 1896
|align=right   |  22 Apr 1898
|align=right   |  5 Jun 1902
|align="center"|  £565,464
|align="center"|  £541,927
|-
| {{HMS|Europa|1897|2}}
|align="center"|  [[John Brown & Company|J&G Thompson]], [[Clydebank]]
|align=right   |  10 Jan 1896
|align=right   |  20 Mar 1897
|align=right   |  23 Nov 1899
|align="center"|  £589,835
|align="center"|  £564,690
|-
| {{HMS|Niobe|1897|2}}
|align="center"|  Vickers, Barrow
|align=right   |  16 Dec 1895
|align=right   |  20 Feb 1897
|align=right   |  6 Dec 1898
|align="center"|  £574,878
|align="center"|  £548,283
|-
| {{HMS|Spartiate|1898|2}}
|align="center"|  [[Pembroke Dockyard]]
|align=right   |  10 May 1897
|align=right   |  27 Oct 1898
|align=right   |  17 Mar 1903
|align="center"|  £680,188
|align="center"|  £654,661
|}

==Notes==
{{reflist|group=note}}

==Citations ==
{{Reflist|2}}

== References ==
* Brown, David K. ''Warrior to Dreadnought: Warship Development 1860–1905''. Caxton Editions 2003. {{ISBN|1-84067-529-2}}
* Chesneau, Roger and Kolesnik, Eugene (Ed.) ''Conway's All the World's Fighting Ships 1860–1905''. Conway Maritime Press, 1979. {{ISBN|0-8317-0302-4}}
* Robert Gardiner (Ed.). ''Conway's All the World's Fighting Ships 1906–1921''. Conway Maritime Press, 1985. {{ISBN|0-85177-245-5}}
* [http://www.worldwar1.co.uk/armoured-cruiser/hms-diadem.html worldwar1.co.uk]
* Jane, Fred T (Ed.) Jane's Fighting Ships 1900
* Jane, Fred T (Ed. Preston, Antony). ''The British Battle-Fleet: Its Inception and Growth throughout the Centuries''.  Republished by Conway Maritime Press, 1997. {{ISBN|0-85177-723-6}}.
* [[Thomas Brassey, 2nd Earl Brassey|Brassey, T.A.]] (ed)[[Brassey's Naval Annual|The Naval Annual 1904]]
* [[Thomas Brassey, 2nd Earl Brassey|Brassey, T.A.]] (ed)[[Brassey's Naval Annual|The Naval Annual 1905]]
* Leyland, J. and [[Thomas Brassey, 2nd Earl Brassey|Brassey, T.A.]] (ed)[[Brassey's Naval Annual|The Naval Annual 1906]]
* [[Thomas Brassey, 2nd Earl Brassey|Hythe, Viscount]] and Leyland, J. (ed)[[Brassey's Naval Annual|The Naval Annual 1914]]

== External links ==
{{Commons category|Diadem class cruisers}}

{{Diadem class cruiser}}
{{WWI British ships}}

{{DEFAULTSORT:Diadem Class Cruiser}}
[[Category:Cruiser classes]]
[[Category:Diadem-class cruisers| ]]
[[Category:Ship classes of the Royal Navy]]