Exercise Verity Exercise Verity was a 1949 multilateral naval training exercise involving 60 warships from the British , French , and Dutch navies for the newly formed Western Union , the precursor to the Western European Union ( WEU ) . A contemporary newsreel described this exercise as involving " the greatest assembly of warships since the Battle of Jutland . " Background . The Treaty of Brussels was signed by the United Kingdom , France , Belgium , Luxembourg and the Netherlands on 17 March 1948 . It was a mutual intergovernmental self - defence treaty which also promoted economic , cultural and social collaboration . The Brussels Pact had cultural and social clauses , and provisions for the setting up of a Consultative Council . The basis for this was that a cooperation organization between Western nations would help stop the spread of Communism . Command structure . The command authority for Exercise Verity was the Western Union Defence Organization ( WUDO ) , the defence arm of the Western Union . Field Marshal the Viscount Montgomery of Alamein was the WUDO ' s senior officer as Chairman of the Commanders - in - Chief Committee . Admiral of the Fleet Sir Rhoderick McGrigor , RN , was in overall command of Exercise Verity . At the time of the exercise , Admiral McGrigor was serving as Commander - in - Chief of the British Royal Navy ' s Home Fleet . The Operation . The 60 - ship fleet gathered in Mount ' s Bay , near Penzance , prior to setting sail for the Bay of Biscay for the week - long exercise . Field Marshal Montgomery held a reception on board the flagship , the aircraft carrier HMS " Implacable " . Prince Bernhard of the Netherlands sponsored a cocktail party aboard the cruiser HNLMS " Tromp " . Field Marshal Montgomery stayed on board the " Implacable " as an observer during the exercise . Submarines , including the highly advanced French boat " Roland Morillot " , made simulated attacks against convoys and naval formations using dummy torpedoes . The exercise included bombers flying from land - based airfields . French and British carriers also launched air strikes , with " Implacable " successfully carrying out strike operations against the enemy ( " White " ) aircraft carrier force led by the light aircraft carriers HMS " Theseus " and the French " Arromanches " . Naval bombardment and convoy escort operations were also carried out . Finally , motor torpedo craft of the Belgian Navy joined other Western Union warships to execute mine - sweeping operations in Weymouth Bay . On 4 July the White force aircraft ( RAF Lancasters and Dutch fighters ) operated searches against the Blue force ( escorted by French aircraft and British flying boats ) as it approached the Bay of Biscay . Later both naval surface forces combined in a simulated convoy - the aircraft carriers standing in for troopships - with Lancasters , Mitchells and Meteors as air cover . Land based fighters and naval strike aircraft practiced attacks with cannon and rockets against the smaller ships and then against the main force of four carriers , the battleship " Anson " and supporting destroyers . The same was practiced the morning of the following day . One unusual example of allied cooperation involved the replacement of the outer wing of a Netherlands Sea Fury fighter aircraft that had been damaged by a bird strike . Since the Royal Netherlands Navy did not provide such elaborate spare parts when the aircraft ' s group deployed to RNAS Culdrose , the damaged Sea Fury received a replacement wing with British markings . Admiral McGrigor summarized the accomplishments of Exercise Verity by noting : " The object of these manoeuvres is to show that we are willing and able to work together in case of aggression . . . I can say straight away that it ' s been a very great success . . . " Force composition . Major naval units included the British battleship ; the British carriers , and ; the French carrier " Arromanches " ; three British and five French cruisers ; and 21 " destroyers and destroyer escorts " . Aviation units included Royal Netherlands Air Force with Mitchell medium bombers and Meteor fighters , Royal Netherlands Navy Fireflies and Sea Furies Royal Netherlands Navy at French Maritime Air Force Dornier and Sunderland flying boats and Wellington bombers , operating from Brest and Lorient . Belgium contributed fighter aircraft in " a preliminary stage " . The RAF forces included Avro Lancaster and Avro Lincoln heavy bombers , Sunderland flying boats and Meteor fighters . Overall control was RAF Coastal Command . " Implacable " carried de Havilland Sea Hornet fighters and Blackburn Firebrand strike aircraft . The British 15th Carrier Air Group operated Fairey Firefly s and Hawker Sea Furies from land bases . Aftermath . When the division of Europe into two opposing camps became unavoidable , the threat of the Soviet Union became much more important than concerns over German rearmament . Western Europe therefore sought a new mutual defence pact involving the United States . The United States recognized the growing threat of the USSR and was responsive to this concept . Secret meetings began by the end of March 1949 between American , Canadian and British officials to negotiate such a trans - Atlantic mutual defence pact . Eventually , it would lead to the formation of the North Atlantic Treaty Organization ( NATO ) with the North Atlantic Treaty signed in Washington , D . C . in 1949 . NATO began forming its own military command structure in 1951 , at which time the headquarters , personnel and plans of the WUDO were transferred to Supreme Headquarters Allied Powers Europe ( SHAPE ) , and SHAPE took over responsibility for the defence of Western Europe . The Treaty of Brussels was amended by the Protocol signed in Paris at the conclusion of the London and Paris Conferences on 23 October 1954 , which added West Germany and Italy to the Western Union , which was renamed the Western European Union .