Operation Calendar (14–26 April 1942) was an Anglo–American operation in the Second World War to deliver 52 Supermarine Spitfire fighter aircraft to Malta. Spitfires were necessary to challenge Axis air superiority over Malta because they had the performance that Hurricane fighters lacked. Aircraft carriers were necessary to get fighter aircraft to positions in the western Mediterranean from which they had the range to reach Malta but British aircraft carriers were busy elsewhere, under repair or too small to deliver enough Spitfires to be effective.
was in European waters and was loaned to the British to ferry a large number of Spitfires in one voyage. Wasp picked up the fighters in the Clyde and became part of Force W, to sail to the Strait of Gibraltar, rendezvous with ships from Force H based at Gibraltar, to make a Club Run, in which 48 of the 52 Spitfires were dispatched to Malta and 47 arrived. Massed air raids by the and led to the rapid destruction or damage to the Spitfires once at Malta. The failure of the Spitfires delivered to Malta led to Wasp making another Club Run in May (Operation Bowery).
Background
Intelligence
Axis
In the autumn of 1941 Axis intelligence agencies had established eleven stations around Gibraltar, the main one at Algeciras. Two of the stations had Spanish agents and others had German and Italians in Spanish uniforms and by early 1942 had gained a fair degree of efficiency. Messages usually reached Berlin within the hour but the British code-breakers at Bletchley Park could decrypt the signals so quickly that the Admiralty knew of a ship arrival at Gibraltar before the authorities there had sent a notification signal. Axis reports were usually accurate enough to name the big ships, except in poor visibility. The Germans began to install infra-red devices and night telescopes, to be more effective in poor weather and in the dark. In (Operation Bay) buildings were put up on either side of the Strait of Gibraltar for the new apparatuses and were operational by April 1942, the Admiralty having warned on 7 March that ships were likely to be detected at night.
British
The British on Malta obtained tactical intelligence from the local Royal Air Force (RAF) Y service unit. The Government Code and Cypher School (GC & CS) at Bletchley Park in England was able to decrypt some Luftwaffe operation orders, which showed that the main effort was to be against British airfields on Malta. The decrypts were infrequent because much of the Axis signals traffic was sent by landline and the time needed to decrypt wireless signals precluded their use for early-warning. The exploitation of radio and wireless transmissions by the Y unit was useful but neither it nor the radar on the island could give sufficient warning of air raids. The air superiority enjoyed by the Axis air forces meant that such warning of raids that was possible was of little tactical value. As soon as a supply convoy left Gibraltar or Alexandria, Axis agents reported it, GC & CS gaining a plethora of decrypts from them which the Admiralty could pass on to the local naval commanders on Axis positions, strengths, reconnaissance practices and the equipment and methods of their bombers and torpedo-bombers. Before a Malta convoy, the RAF conducted many photographic sorties, revealing more about Axis air force locations and strengths but this reached only as far as Naples. The authorities in London had a grandstand view but for early warning of attacks, until May 1942, convoys were reliant on aerial patrolling, radar and lookouts.
Malta
As Malta began to run short of supplies, Operation MG 1 was mounted to escort Convoy MW 10 from Alexandria on 21 March. The convoy was the subject of a tentative attack by an Italian fleet; the Italians inflicted severe damage on several escorts in the Second Battle of Sirte but the weaker British force fended off the Italian fleet. The attack on the convoy led to its dispersal which caused a delay and it reached Malta in the morning and not at night as planned, leaving the merchant ships exposed to Axis air attack. In the next 48 hours, all the merchant ships were sunk off Malta or at their moorings; barely of supplies were unloaded.
By the end of April 1942, Axis bombing had smashed the docks, ships, aircraft and airfields and the bombers began attacks on army camps, barracks, warehouses and road junctions, the preliminaries of invasion. After 18 April, German bombing suddenly stopped and Italian bombers took over, regularly bombing with small formations of aircraft. During the month, Axis aircraft flew more than against the RAF all but which were fighter sorties. The British lost down in combat against losses, during the dropping of of bombs, three times the March figure, falling on the docks, on airfields.
The bombing killed left seriously wounded and demolished or damaged Good shelters existed but some of the casualties were caused by delayed-action bombs. Three destroyers, three submarines, three minesweepers, five tugs, a water carrier and a floating crane were sunk in port and more ships damaged. The island continued to function as a staging post but the Axis bombing neutralised Malta as an offensive base. Two boats of the 10th Submarine Flotilla had been sunk, two were damaged in harbour and on 26 April the flotilla was ordered out because of mining by small fast craft, which were undetectable by radar and inaudible during the bombing; the surviving minesweepers were too reduced in numbers to clear the approaches. The governor, Sir William Dobbie had given a deadline of mid-June for the exhaustion of the food on the island and could only be met by the delivery of substantial supplies of food, fuel, ammunition and equipment brought by sea.
Malta convoys A supply convoy to Malta in January 1942 lost one of four ships and an escort was sunk by a U-boat; the February convoy suffered the loss of its three merchant ships to aircraft attack. During the March convoy, the escorts were forewarned by a submarine sighting and decrypts from the Italian C 38m coding machine that an Italian fleet had sailed from Taranto, leading to the Second Battle of Sirte on 22 March 1942, the defence of the convoy by the 15th Cruiser Squadron which forced the battleship , the heavy cruisers , , one light cruiser and ten destroyers to turn away, having inflicted little serious damage to the British escorts and none to the convoy. Two of the four merchantmen were sunk by air attack near Malta and the other two were sunk at their moorings when the unloading of their cargoes had barely begun. Despite the ferrying of fighter aircraft to Malta by aircraft carrier, submarines had to be used to ferry aviation fuel.
Axis convoys
The Axis air offensive against Malta and the losses inflicted on the Mediterranean Fleet by Italian human torpedoes of the and other losses made it much harder for the British to attack convoys to Libya. On 4 January, massed air attacks on Malta coincided with the Italian M43, six merchant ships crossing from Italy escorted six destroyers and five torpedo boats, a close escort of a battleship, four light cruisers and five destroyers and a distant escort of three battleships, two heavy cruisers and eight destroyers. Intelligence decrypts revealed to the British the timing and route of the battleship convoy, with reconnaissance reports from aircraft. Bombers from Malta and Cyrenaica missed the convoy and Force K in Malta remained in port. The convoy arrived on 5 January, a notable Axis success; British submarine attacks on the convoy on its return journey failed. On 22 January, T18, another battleship convoy, got four of five ships to Tripoli. On 21 February in K7, three groups of merchant ships departed Italy with another elaborate battleship escort, a British air attack was defeated by German fighters on 22 February and the convoy arrived the next day. The Italians sent eleven convoys in February, thirteen of the fifteen ships arriving, (99.2 per cent) of the supplies despatched being unloaded; submarines sank three of the eleven ships making the return journey.
Convoy V5 sailed on 7 March from several ports and attacks failed as they did on the return convoy. on 15 March brought four merchant ships to Tripoli on 18 March. The had used much of its fuel oil on the battleship convoys, when German oil deliveries had been suspended and the Italians had to return to smaller escort operations. Four ships departed Italian ports on 17 and 18 March, one hitting a mine near Tripoli and the rest arriving, the danger of attacks from Malta having diminished considerably. Fourteen convoys had sailed for Tripoli in March and eighteen of twenty ships survived the journey, of supplies arrived (82.7 per cent). On 4 April, six ships in three convoys arrived at Tripoli and delivered six merchantmen on 16 April. The decline of Malta as an offensive base led the British to rely on submarines, which sank a light cruiser and six freighters and RAF bombers from Egypt bombing Libyan ports. In April, of supplies arrived (99.2 per cent).. Italian ships were at their safest from April to mid-July 1942, convoys sailing from Malta, escorted by a couple of aircraft.
+Italian convoy deliveries to Libya.MonthNon-fuel (tons)Fuel (tons)Losses (%)NotesApril102,00048,000<1With Malta suppressed and western Cyrenaica lost, 750 aircraft anti-shipping sorties had little effect on Italian convoys.
Prelude
Club Runs
Operation MG 1
Operation MG 1 (20–26 March) to escort Convoy MW 10 to Malta, succeeded but hardly any of the supplies reaching Malta survived Axis air attacks. Malta had been neutralised as an offensive base by the loss of 126 aircraft on the ground and twenty in the air. The RAF withdrew most of its bombers and reconnaissance aircraft and the Navy evacuated most of its ships; Axis convoys could now be run to Libya against scant opposition. The demands on the Home Fleet for escorts for the Arctic Convoy PQ 16 in May 1942, led Churchill and the War Cabinet to decide that merchant ships could not be risked on Malta convoys until its air defences had been reinforced. The Air Officer Commanding, Air H.Q. Malta, Sir Hugh Lloyd wrote that
Recent Club Runs to deliver aircraft from Gibraltar had been dogged by failures and inefficiency; the new external fuel tanks for Spitfires had proved inadequate, forcing the cancellation of the Club Runs Operation Spotter I and Operation Picket I Club Runs. The deck of was too short for enough Spitfires with long-range tanks to be accommodated, was in dock for emergency repairs and the fleet carriers had lifts that were too narrow for the wingspan of Spitfires or were busy in the Indian Ocean. Churchill made a request to the US president, Franklin D. Roosevelt, for the use of the American aircraft carrier, (Captain John W. Reeves, Jr.), that was in British waters, which Roosevelt granted.
Royal Air Force The RAF had chosen aircrew for previous Spitfire reinforcements to Malta according to availability. For Operation Calendar, 601 (County of London) Squadron (Squadron Leader John Bisdee) and 603 (City of Edinburgh) Squadron (Squadron Leader Lord David Douglas-Hamilton) were chosen. The Spitfires flew from RAF Prestwick to the airstrip at RAF Renfrew.
Operation Calendar 14–16 April 1942
Wasp and its destroyers and sailed for the River Clyde, cheered on by crowds of civilians and the workers at the John Brown shipyards. By 14 April, Wasp had taken on 52 Spitfires Mk Vc (trop) at King George V dock at Shieldhall. To make room for the Spitfires, the F4F-3 Wildcat fighters of VF-71 were accommodated on the flight deck. Wasp and its destroyers sailed that day and were joined by the British battlecruiser (Commodore Charles Daniel) and the destroyers , , and , forming Force W. The ships sailed west-about Ireland and then southwards for the Bay of Biscay.