View source for French cruiser Pluton

{{Short description|Minelayer of the French Navy}}
{{Other ships|French ship Pluton}}

{|{{Infobox ship begin}}
{{Infobox ship image
|Ship image=Pluton minelaying cruiser.svg
|Ship caption=Approximate outlines of ''Pluton''
}}
{{Infobox ship career
|Hide header=
|Ship country=France
|Ship flag={{shipboxflag|France|naval}}
|Ship name=''Pluton''
|Ship namesake=[[Pluto (mythology)|Pluto]]
|Ship builder=[[Arsenal de Lorient]]
|Ship original cost=102,671,658 [[French franc|francs]]
|Ship yard number=
|Ship way number=
|Ship laid down=16 April 1928
|Ship launched=10 April 1929
|Ship commissioned=25 January 1932
|Ship recommissioned=
|Ship decommissioned=
|Ship maiden voyage= 
|Ship in service=
|Ship out of service=
|Ship renamed=
|Ship refit=
|Ship struck=
|Ship homeport=
|Ship identification=
|Ship honors=
|Ship fate=Sunk by accidental explosion, 13 September 1939
|Ship notes=
|Ship badge=[[File:Pluton insignia.svg|80px]]
}}
{{Infobox ship characteristics
|Hide header=
|Header caption=
|Ship type=[[Minelayer|Minelaying cruiser]]
|Ship displacement=*{{cvt|5300|t|LT|lk=on}} ([[Displacement (ship)#Standard displacement|standard]])
*{{convert|6214|t|LT|abbr=on}} ([[full load]])
|Ship length={{convert|152.5|m|ftin|abbr=on}}
|Ship beam={{convert|15.5|m|ftin|abbr=on}}
|Ship draft={{convert|5.2|m|ftin|abbr=on}}
|Ship power=*4 × [[du Temple boiler]]s
*{{cvt|57000|shp|kW|lk=on}}
|Ship propulsion=2 × shafts; 2 × geared [[steam turbine]]s
|Ship speed={{convert|30|kn|lk=in}}
|Ship range={{convert|4510|nmi|lk=in|abbr=on}} at {{convert|14|kn}}
|Ship capacity=1000 troops
|Ship complement=513 men
|Ship armour= 
|Ship armament=*4 × [[Canon de 138 mm Modèle 1923|{{cvt|138.6|mm|1}}]] guns
*10 × [[Canon de 37 mm Modèle 1925|{{cvt|37|mm|1}}]] [[AA gun]]s
*220–270 [[Naval mine|mine]]s
|Ship notes=
}}
|}

'''''Pluton''''' was a fast [[Minelayer|minelaying cruiser]] built for the [[French Navy]] in the late 1920s. She was also able to carry 1,000 troops on her mine deck as a fast troop transport. Shortly after completion she was modified and became a gunnery training ship, replacing the elderly [[armored cruiser]] {{Ship|French armoured cruiser|Gueydon||2}}. Shortly before the beginning of [[World War II]], she reverted to her original role and most of the gunnery training equipment was removed. She was sent to [[Casablanca]], in [[French protectorate of Morocco|French Morocco]], when the war began to lay a minefield, but the order was cancelled a day later and she was ordered to disembark her [[naval mine]]s. She exploded while landing her still-fuzed mines on 13 September 1939.

==Design==
The [[Marine Nationale]] decided to build a fast minelayer as part of its 1925 Naval Programme after the British {{HMS|Adventure|M23|6}} made her debut in the early 1920s. ''Pluton'' was similar in many respects, also being armed with four single destroyer-caliber guns, but was smaller and faster. She could also be used as a fast transport for up to 1,000 troops. The sides of the mine deck were normally open to the weather, but metal panels could be used to close it off when carrying troops.<ref>Guiglini & Moreau, pp. 153, 155</ref>

===General characteristics===
''Pluton'' was {{convert|152.5|m|ftin|abbr=on}} long [[Length overall|overall]]. She had a [[Beam (nautical)|beam]] of {{convert|15.5|m|ftin|abbr=on}} and a [[Draft (hull)|draft]] of {{convert|5.2|m|ftin|abbr=on}}. Her longitudinally framed hull was subdivided by 15 transverse watertight [[Bulkhead (partition)|bulkhead]]s. [[Duralumin]] was extensively used in the superstructure to save weight, but this resulted in corrosion problems and strength issues. She was fitted with a single counterbalanced rudder powered by an electric motor that was too weak for the job. Her turning circle was {{convert|875|m|yd|abbr=on}} with 25° of rudder at {{convert|27|kn|km/h mph|lk=in|abbr=on}}, larger than that of the {{convert|8000|t|LT|abbr=on}} light cruiser {{ship|French cruiser|Duguay-Trouin|1923|2}} which was {{convert|30|m|ftin|abbr=on}} longer. She was totally unarmored and relied upon her [[watertight subdivision]] for survival.<ref>Jordan, pp. 21–22</ref>

===Propulsion===
''Pluton'' had a two-shaft unit machinery layout with alternating boiler and engine rooms. Her Bréguet single-reduction impulse geared steam turbines were designed for {{convert|57000|shp|kW|lk=on}}, but made {{convert|64705|shp|kW|abbr=on}} on trials. Four [[du Temple boiler]]s powered the turbines at a pressure of {{convert|20|kg/cm2|kPa psi|lk=on|abbr=on}}.<ref name=j22>Jordan, p. 22</ref> An auxiliary boiler was fitted to heat or cool the ship's [[Magazine (artillery)|magazine]]s and provide drinking water. Each [[Propeller shaft (ship)|propeller shaft]] drove a three-bladed {{convert|4.08|m|ftin|abbr=on}} bronze propeller for a designed speed of {{convert|30|kn|lk=in}}, but she achieved {{convert|31.4|kn}} on trials.<ref>Guiglini & Moreau, pp. 155, 158</ref> {{convert|1150|t|LT|abbr=on}} of [[fuel oil]] was carried which was originally calculated to provide an endurance of {{convert|7770|nmi|lk=in}} at {{convert|14|kn}}, but it was revised downwards to {{convert|4510|nmi|abbr=on}} once she entered service because the demands of her auxiliary machinery had been seriously underestimated. A pair of {{convert|200|kW|adj=on}} [[turbo generator]]s provided electricity at 235&nbsp;volts. Two {{convert|100|kW|adj=on}} [[diesel generator]]s were mounted in the aft engine room to provide power while in harbor and a third was installed in a special compartment on the first deck for emergency use.<ref>Jordan, pp. 22–23</ref>

===Armament===
''Pluton'' was originally intended to carry two single turrets, one each fore and aft, with {{convert|203|mm|in|0|abbr=on}} guns, four {{convert|75|mm|in|2|abbr=on}} [[Anti-aircraft warfare|anti-aircraft]] (AA) guns and four light {{convert|37|mm|in|2|abbr=on}} AA guns. However four {{convert|138|mm|in|1|abbr=on}} guns were substituted for the 203&nbsp;mm guns before construction began and six more 37&nbsp;mm guns were added in lieu of the 75&nbsp;mm guns during construction although the baseplates for the 75&nbsp;mm guns were retained for future use.<ref name=g3>Guiglini & Moreau, p. 153</ref>

The four [[Canon de 138 mm Modèle 1923|138 mm]] 40-[[Caliber (artillery)|caliber]] guns were on M1924 mounts with [[gun shield]]s. Two guns each were fore and aft in [[Superfire|superfiring]] positions on the centerline. Their elevation limits were -10° to +35° and they had a 270° [[arc of fire]]. Their rate of fire was a nominal eight to nine rounds per minute, but proved to be considerably less in service. They had a maximum range of about {{convert|18200|m|yd|abbr=on}} with a {{convert|40|kg|lb|abbr=on}} shell at a muzzle velocity of {{convert|700|m/s|ft/s|abbr=on}}. 150&nbsp;rounds were provided for each gun. One powder and one shell magazine served each pair of guns, each of which had their own individual hoist.<ref name=j3>Jordan, p. 23</ref>

Ten [[Canon de 37 mm Modèle 1925|37 mm]]/50&nbsp;cal semi-automatic AA guns were carried by ''Pluton''. Two were fitted on the foredeck, six amidships between the funnels and two on a platform at the stern. 10,000&nbsp;rounds were carried with 144 rounds in ready-use boxes near each gun.<ref name=j3/> The guns could depress 15° and elevate to 80°. They fired {{convert|0.725|kg|lb|abbr=on}} shells at a muzzle velocity of {{convert|810|m/s|ft/s|abbr=on|0}}. Their effective anti-aircraft range was less than {{convert|5000|m|sp=us|0}}.<ref>{{cite web|url=http://www.navweaps.com/Weapons/WNFR_37-50_cail_m1933.htm|title=France 37 mm/50 (1.46") Model 1925 37 mm/50 (1.46") CAIL Model 1933 |date=28 November 2009|publisher=Navweaps.com |access-date=6 February 2010}}</ref> All of these guns—except for the pair on the stern—were removed shortly after ''Pluton'' was commissioned in 1932.<ref name=g6>Guiglini & Moreau, pp. 160, 166</ref>

Twelve obsolete {{convert|8|mm|in|3|abbr=on}} [[Hotchkiss M1914 machine gun|Hotchkiss M1914]] [[machine gun]]s were carried in six twin mounts. Two mounts were on top of the bridge, two atop the after boiler room ventilator housing and two just forward of the tripod mainmast. 48,000&nbsp;rounds were provided for them. They were removed shortly after ''Pluton'' was commissioned in 1932.<ref name=g6/>

''Pluton'' was designed to carry 220 {{convert|1500|kg|lb|abbr=on}} Sautter-Harlé mines, but had space for 30 extra, for a total of 250. They were carried on the first deck, or mine deck, using a system of four rails along the sides of the ship and moved via chain-drives. Each pair of rails converged on a turntable at the forward end of the rails and a transverse spur connected the two turntables. The spur facilitated loading mines from one side of the ship and allowed mines to be moved to each of the rails. The rails ended in four ramps at the stern of the ship that sloped down at a 30° angle to minimize the shock of impact when the mines were released from the chain drive. Up to 270 of the smaller Bréguet B4 mines could be carried.<ref>Guiglini & Moreau, pp. 160–61</ref>

==Service==
She entered service with the French [[Commander-in-Chief, Mediterranean (France)|Mediterranean Fleet]] in 1932. ''Pluton'' experienced many teething problems, particularly with the machinery. Shortly after she was commissioned the Navy decided to give her an extra role as a gunnery training ship and she entered [[Toulon]] Dockyard for the necessary modifications on 24 October 1932. Quarters for 40 men were added on the mine deck. Most of the 37-mm AA guns and all of the 8&nbsp;mm machine guns were replaced by four 50-caliber 75&nbsp;mm Canon de 75&nbsp;mm Mle 22 or 24 AA guns and 12 [[13.2 mm Hotchkiss machine gun|{{convert|13.2|mm|in|2|abbr=on}} Hotchkiss machine gun]]s on six twin mounts, two mounts where the 37&nbsp;mm guns had been mounted on the foredeck and four between the funnels.<ref>Guiglini & Moreau, pp. 166, 171</ref> The 75&nbsp;mm guns had a maximum depression of 10° and a maximum elevation of 90°. They fired a {{convert|5.93|kg|adj=on|sp=us}} shell at a muzzle velocity of {{convert|850|m/s|ft/s|abbr=on}} at a rate of fire of 8–18 rounds per minute and had a maximum effective ceiling of {{convert|8000|m|ft|abbr=on}}.<ref>{{cite web|url= http://www.navweaps.com/Weapons/WNFR_3-50_m1922.htm|title=French 75 mm/50 (2.95") Model 1922, 1924 and 1927|date=24 March 2007|publisher=Navweaps.com|access-date=8 February 2010}}</ref> The Hotchkiss guns had a cyclic rate of fire of 450 rounds per minute, but the practical rate was between 200 and 250 rounds per minute to allow for reloading its 30-round magazines. They had a theoretical ceiling of {{convert|4200|m|ft|abbr=on}}.<ref>{{cite web|url=http://www.navweaps.com/Weapons/WNFR_13mm_aamg.htm|title=France 13.2 mm/76 (0.52") Model 1929 |date=28 November 2009| publisher= Navweaps.com|access-date=8 February 2010}}</ref> A simple [[Fire-control system#Naval fire control|fire-control director]] was added for the 138&nbsp;mm guns and 15 additional rangefinders were installed for use by the Rangefinding School.<ref name=g71>Guiglini & Moreau, p. 171</ref>

''Pluton'' spent much of 1933–1935 in dockyard hands after finishing her first round of modifications on 27 April 1933. She was refitted four times during this period to add more gunnery equipment and to rectify some of her defects. These included reinforcement of her superstructure where it had been damaged by the [[Muzzle flash|muzzle blast]] from her 138&nbsp;mm guns and replacement of her corroded aluminum ladders and booms with steel ones. A high-angle fire-control director for her 75&nbsp;mm guns was added, two of her 75&nbsp;mm gun were converted to powered, remotely controlled mounts, gun shields were added to the 75&nbsp;mm guns to protect their crews from blast and facilities for another 40 men was installed on her mine deck.<ref name=g71/>
[[File:Les restes du Pluton.jpg|thumb|The wreckage of ''Pluton'' at Casablanca]]
In 1936, an experimental twin 13.2&nbsp;mm gun mount with a gun shield was added between the starboard 75-mm guns and more rangefinders were added to bring her total up to 31. Her boilers and condensers were repaired in a refit between 25 November 1936 and 13 March 1937. Later that year ''Pluton'' had a major refit that involved repair of her turbines, replacement of her 138&nbsp;mm fire-control director by one of the type used by the {{convert|8000|t|LT|abbr=on}} [[light cruisers]] and the transfer of the foredeck 13.2&nbsp;mm machine guns to positions on the forward superstructure. Her last refit, from 15 November 1938 – 15 February 1939, retubed two boilers, enclosed the AA director to protect it from the weather, improved the remote control of the 138&nbsp;mm guns and added gun shields to each of the twin 13.2&nbsp;mm mounts.<ref>Guiglini & Moreau, p. 172</ref>

''Pluton'' was transferred to [[Lorient]] on 10 May 1939 when the French Navy formed the 5<sup>e</sup> Escadre there which controlled all training ships and planned to convert her into a full-time training ship as consort to the training cruiser {{ship|French cruiser|Jeanne d'Arc|1930|2}} on 1 June 1940.<ref name=j8>Jordan, p. 28</ref> She would have been renamed ''La Tour d'Auvergne'' at that time, as the name ''Pluton'' was reserved for mine warfare ships in the French Navy.<ref name=g3/>

As war approached, it was decided to retain her as a minelayer and most of the extra fire control equipment was removed. She was transferred to [[Brest, France|Brest]] as part of the reorganization of the 5<sup>e</sup> Escadre. She sailed for Casablanca, French Morocco on 2 September with 125 Bréguet mines embarked. She was ordered to lay a defensive minefield there on 4 September, but this order was rescinded the next day, after the mines had already been fuzed, and the ship was ordered to disembark the mines. While landing the mines on 13 September one of them exploded, destroying the ship and killing 186 people. A further 73 crewmen and 47 others were injured and significant damage was caused by flying debris.<ref name=j8/> Three trawlers (''Etoile du Matin'', ''Marie Merveilleuse'', and ''Sultan'') were sunk by the explosion, and the auxiliary minesweepers ''Charcot'', ''Gosse'', and ''Chellah'' damaged beyond repair. Two other auxiliary minesweepers, ''Grodin'' and ''Alcor'', were damaged but able to be repaired.<ref>{{Cite web|url=http://www.naval-history.net/xDKWW2-3909-06SEP01.htm|title = Polish Navy at War, September 1939}}</ref> One gun and some armor was salvaged during the war, but demolition work did not begin until October 1952 and was completed by July 1953.<ref>Guiglini & Moreau, p. 232</ref>

== See also ==

* [[HMS Adventure (M23)]]
* [[USS Terror (CM-5)]]
* [[Abdiel-class minelayer]]
* [[Robert H. Smith-class destroyer]]

==Notes==
{{Reflist|30em}}

==Bibliography==
*{{cite journal|last=Guiglini|first=Jean|author2=Moreau, Albert |year=1992|title=The First Light Cruisers of the 1922 Program: The Minelaying Cruiser Pluton, Pts. 1–2|journal=Warship International |publisher=International Naval Research Organization|volume=XXIX|issue=2–3| pages=152–173, 225–243|issn=0043-0374|name-list-style=amp}}
*{{cite book|last=Jordan|first=John|chapter=The Minelaying Cruiser Pluton|editor=Preston, Antony| publisher=Conway's Maritime Press|location=London|year=2004|title=Warship 2004|pages=21–28| isbn=0-85177-948-4|editor-link=Antony Preston}}

{{French cruiser Pluton}}
{{WWII French ships}}
{{September 1939 shipwrecks}}
{{good article}}

{{coord missing|Mediterranean}}

{{DEFAULTSORT:Pluton}}
[[Category:Cruisers of the French Navy]]
[[Category:Ships built in France]]
[[Category:1929 ships]]
[[Category:World War II cruisers of France]]
[[Category:World War II shipwrecks in the Atlantic Ocean]]
[[Category:Maritime incidents in September 1939]]
[[Category:Minelayers of the French Navy]]
[[Category:Ships sunk by non-combat internal explosions]]
[[Category:Fast minelayers]]