Vian returned to the UK shortly before the
Second World War broke out. An appointment to command the boys' training establishment was cancelled, and he was appointed to command of the
11th Destroyer Flotilla. This flotilla had been recently activated from reserve and consisting of seven old s plus his own ship, , based first at
Plymouth then at
Liverpool, with the role of escorting Atlantic
convoys. There was an ineffective brush with a
U-boat. A change in policy required Vian, as a
Captain (D), to operate from shore, the better to command his flotilla. Early in 1940 he moved, this time to command of the
4th Destroyer Flotilla, the famous s. The
German and
Norwegian governments protested that this was a violation of international law and of Norwegian neutrality. However, occurring during a quiet stage in the war, the incident was widely publicised in Britain. Vian was awarded the
Distinguished Service Order (DSO) for this successful action, the citation was published in a supplement to the
London Gazette of 9 April 1940 (dated 12 April 1940, and read:
Naval actions The Germans invaded Norway on 9 April 1940 and Vian, now in
Afridi, was engaged in a number of operations against German shipping and warships and in support of Allied troops. On 9 April 1940, Vian's destroyers were escorting two cruisers ( and ) off Bergen when they came under heavy German air attack. became isolated and was sunk. From 15 to 17 April,
Afridi assisted and protected British troop landings at Namsos (
Operation Maurice), which were a part of a planned pincer movement to seize
Trondheim.
Afridi later assisted the evacuation of Namsos and the rescue of the survivors of the , during which, on 3 May,
Afridi was bombed and sunk; the survivors were rescued by destroyers and . Vian was
mentioned in despatches for his part in the action. On the night of 13/14 October, Vian, now re-established in HMS
Cossack and with HMS
Ashanti,
Maori and
Sikh, attacked a small German convoy off
Egerö light. Although the operation's success was over-stated (just one ship was sunk and later refloated), Vian was awarded a
bar to his DSO. On 22 May 1941, Vian, in HMS
Cossack, with several destroyers, provided additional escort to troop convoy WS8B en route from Glasgow to the Indian Ocean. On 25 May, Vian's destroyers (HMS
Cossack,
Maori,
Sikh,
Zulu and ) were detached from the convoy to join the search for the German battleship . Eventually, Vian's flotilla participated in the destruction of
Bismarck. While the main battle fleet awaited daylight, they, in a series of night attacks, harried the German ship. They failed to score a hit in the darkness, but their activities fixed the German's position and denied the crew much-needed rest before the main battle on 27 May. Afterwards, they escorted back to Scotland. Vian received a second bar to his DSO for this action. Vian was promoted to
rear admiral on 8 July 1941, by special order of the
First Sea Lord, Sir
Dudley Pound. During July and August, 1941, Vian was involved in liaising with the
Soviet Navy to assess their readiness and to investigate the practicalities of a British naval force being based at
Murmansk or nearby. In the event, Vian advised against this, but in September, 1941, he commanded Force K, a naval force that supported an
Anglo-Canadian raid and demolition on the Norwegian archipelago of
Spitsbergen. The intention was to clear out any German garrison (there was none), destroy the coal mines and coal stocks and evacuate the Russian miners. The troops were aboard the liner , escorted by two Royal Navy cruisers, and and three destroyers: , and and several smaller ships. The operation was successful and during Force K's return, a German convoy was intercepted and the German training cruiser was sunk. Malta was still in a desperate state and another convoy (MG1) was run in March 1942. This time, the Italian Navy made a more determined attempt to intercept the convoy, leading to the
Second Battle of Sirte. Vian's force of cruisers and destroyers, using threat and concealment by smoke, managed to hold off the Italians while the convoy escaped. The naval action was portrayed as a tactical success against a greatly superior enemy, although the convoy's progress was sufficiently delayed to leave it vulnerable to air attacks and all four transports were sunk and the bulk of the supplies were lost. Despite this, Vian received a personal letter of congratulation from
Winston Churchill and he was appointed a
Knight Commander of the Most Excellent Order of the British Empire (KBE). In June 1942, Vian's force provided escort for the
Operation Vigorous convoy from
Haifa and
Port Said. This was a part of a sequence of movements but it was rebuffed by strong surface and air forces and returned. After this failed operation, Vian's health deteriorated and he was sent back to Britain in September 1942. During a delay in the journey in west Africa, he caught
malaria and was not passed fit for service until January, 1943. In January, he was mentioned in despatches for "outstanding zeal, patience and cheerfulness and for setting an example of wholehearted devotion to duty without which the high tradition of the Royal Navy could not have been upheld". Vian's physical condition was now considered to debar him from further sea service and in April 1943 he was appointed to the planning staff for the invasion of Europe. Probably much to his relief,
Normandy landings In November 1943, Vian returned to the UK as commander of Force J in preparation for D-Day and in January 1944, he was appointed commander of the Eastern Task Force (in ), supporting the D-Day
landings in Normandy. He was appointed
Companion of the Order of the Bath (CB) in the
King's Birthday Honours, which coincided with the early stages of the invasion. After the success of the landings, he was appointed
Knight Commander of the Order of the Bath (KCB) "for distinguished services in the planning and execution of the successful landings".
British Pacific Fleet in 1945. The blackened funnel is due to damage from a
kamikaze attack. In November 1944, Vian became the commander in charge of air operations of the
British Pacific Fleet (Flag Officer Commanding,
1st Aircraft Carrier Squadron, British Pacific Fleet and Second in Command, British Pacific Fleet, in ). The first operations of Vian's new command were against Japanese oil and port installations in
Sumatra (Operations
Cockpit,
Transom,
Lentil and
Meridian). These served to damage the enemy's capabilities, distract his attention from events elsewhere and provide experience for the British and Commonwealth crews in the procedures that they would use while working with the Americans in the western Pacific. The U.S. aircraft carrier, , participated in the training exercises and the first two operations. Vian was mentioned in despatches once again for "bravery, skill and devotion to duty". Once in the Pacific, the BPF operated as Task Force 57 from March 1945, providing air support for the American invasion of
Okinawa (Operation Iceberg). Their role was to interdict the
Sakishima Islands, suppressing Japanese air operations. Vian's carriers were externally resistant to the determined suicide attacks, returning to active service within hours. He was promoted to
vice admiral on 8 May 1945. ==Post war==