{{Short description|Proposed British offensive during World War II}} {{morefootnotes|date=November 2012}} '''Operation Catherine''' was a proposed Baltic Sea offensive by the United Kingdom's Royal Navy to be undertaken in early 1940.<ref>{{cite book |title=Churchill and Finland: A study in Anticommunism and Geopolitics |last=Ruotsila |first=Markku |year=2005 |publisher=Routledge |isbn=978-0-415-34971-0 |page=74 }}</ref> It aimed at interdicting German seaborne commerce with the Soviet Union, Sweden, Finland, Estonia and Latvia. In particular, an objective was to stop the flow of Swedish iron ore to Germany. The driving force behind the project was the First Lord of the Admiralty Winston Churchill, and the head of planning was Admiral of the Fleet Lord Cork. Events overtook the proposed operation and resulted in its cancellation.
==Plan== Churchill proposed a substantial naval squadron: three ''Revenge''-class battleships, an aircraft carrier, five cruisers, two destroyer flotillas, submarines and supporting auxiliaries. The battleships would need to be significantly modified to resist air and submarine attack to pass through the shallow waters.{{Citation needed|date=May 2019}} {{HMS|Royal Sovereign|05|6}} would have been fitted with very large bulges to her hull to make her {{cvt|140|ft}} wide to increase her buoyancy and thus reduce her draught by {{cvt|9|ft}} even after the addition of {{cvt|4|to|5|in}} of deck armour (some {{cvt|2000|LT}} of armour would be used in total). Only two of her main turrets would be retained, but elsewhere, the elevation for those guns would be 30 degrees. In the new state, her top speed would have been about {{cvt|13|–|14|kn}} in action.<ref>Brown, DK ''Nelson to Vanguard'' p. 155</ref> As well as cutting off German iron ore supplies, Churchill anticipated that the show of force would encourage the Scandinavian nations to join the war against Nazi Germany.{{Citation needed|date=May 2019}}
==Objections== The First Sea Lord Admiral Sir Dudley Pound opposed the plan for several reasons. The armour plating was in short supply and was needed elsewhere; the three battleships were badly needed, particularly if Italy and Japan also declared war; the impact of air power was underestimated in the plan; and the loss of such a squadron would encourage Italy and Japan to declare war.{{Citation needed|date=May 2019}}
==Cancellation== Despite those cogent arguments and widespread opposition, Churchill continued to push hard for Catherine.<ref name=Regan /> Pound avoided a head-on argument and apparently co-operated while he pointed out problems.<ref name=Regan /> Finally, on 20 January 1940, Churchill cancelled the operation.<ref name=Regan>{{cite book |title=Geoffrey Regan's Book of Naval Blunders |url=https://archive.org/details/geoffreyregansbo0000rega |url-access=registration |last=Regan |first=Geoffrey |author-link=Geoffrey Regan |year=2001 |publisher=André Deutsch |isbn=0-233-99978-7 |pages=76–77}}</ref>
==See also== * Plan R 4 * Operation Pike * Franco-British plans for intervention in the Winter War * Anglo-German Naval Agreement of 1935 * British submarine flotilla in the Baltic * Baltic Project - a First World War plan for British intervention in the Baltic
==References== {{reflist}}
== External links == * [http://www.webatomics.com/jason/catherine.html World War II magazine] Article describing Churchill's plan to convert ''Revenge''-class battleships into "armoured turtles" to invade the Baltic Sea in 1940.
{{DEFAULTSORT:Catherine}} Category:Cancelled military operations involving the United Kingdom Category:Baltic Sea operations of World War II Category:Military operations directly affecting Sweden during World War II Category:Cancelled military operations of World War II