According to Wikipedia Malta has been besieged four times. For the reason of "disambiguation" - this is the one in WW2. This timeline has been transcribed from the memorial:
June 1940: Italy declares war on Britain; Malta is now only 100 miles from Axis Airfields. Defences are three obsolete fighters and a few guns.
July 1940: The first convoys arrive. Air raids total 80 already.
August 1940: More fighters and better guns arrive; civilian population evacuated from target areas.
September 1940: Two more convoys arrive with troops and equipment; Malta is to become an allied fortress in the Mediterranean.
October 1940: More fighters and additional airfields commissioned.
November 1940: Torpedo bombers attack the Italian fleet at Taranto with devastating effect, a strategy later copied by the Japanese at Pearl Harbour.
December 1940: The Italian army is defeated in North Africa forcing the Germans to send massive reinforcements. Striking forces from Malta cause so much damage to axis supply lines the axis high command decide to annihilate the island. The Luftwaffe moves to Sicily and begin round-the-clock attacks on Malta.
January 1941: Axis bombers attack and damage the British carrier Illustrious in a convoy to Malta. The ship arrives at Malta for emergency repairs and is subjected to three days of ceaseless bombing before leaving to the USA. 39 axis planes are lost in the blitz for only 2 allied fighters.
February 1941: The attacks continue; the civilian population are moved into rock shelters underground. Air raids now total 400.
March 1941: Four ships arrive in convoy with essential food, ammunition and fuel; they are bombed incessantly on their approach and in harbour.
April 1941: The carrier Ark Royal delivers another consignment of new Hurricane fighters.
May 1941: Malta’s fighter defences are strengthened and reorganised; a bombing squadron is added to attack axis supplies to North Africa.
June 1941: Axis forces invade and occupy Crete with airborne troops, a similar plan is proposed for Malta.
July 1941: Sixteen Italian torpedo boats attack a newly arrived convoy in Grand Harbour; all are destroyed by the defences.
August 1941: The siege is gripping more strongly, food is severely rationed, the air attacks continue incessantly.
September 1941: Eight ships reach Malta in convoy with vital food, fuel and stores. Malta striking forces are now destroying half of all axis supplies being sent to North Africa.
October 1941: Food is desperately short, 3 British submarines shuttle in supplies under water to avoid the air attacks. Rationing is made more severe.
November 1941: Malta striking forces are reinforced and increase axis losses to convoys to North Africa. Axis air forces increase the attempts to subdue Malta.
December 1941: Air raids increase to 175 in this month alone; the entire civilian population is now conscripted into the defence of the island. Everyone lives underground in rock shelters. This memorial is quarried from that very same rock.
January 1942: The axis determination to eradicate Malta continues with no demarcation between months; some bombing raids last up to 36 hours, during this month there are 263 of them. Food, fuel and ammunition run dangerously low.
February 1942: An allied convoy from Alexandria is attacked and destroyed on its way to Malta; the supply situation becomes even more critical. What food there is, is now contaminated with the taste of high explosive.
March 1942: With great determination, two fresh deliveries of Spitfire fighters are made by aircraft carriers. Three ships arrive with 5000 tonnes of supplies which are discharged under ceaseless bombing. 177 axis aircraft are destroyed.
April 1942: Raids are now between 4 and 10 per day in waves of 100 or more aircraft. By now, 15,500 buildings have been obliterated but civilian casualties are mercifully light at 1,104 thanks to the shelters hewn into the living rock of Malta. Air raids now total 5,807 accounting for more than 6,557,231 kilos of high explosive bombs. Food is shared between the entire population via communal “victory” kitchens. Ammunition is in very short supply. As the raids pass the 2000 mark, King George VI awards the entire island population of Malta the George Cross in recognition of their gallantry in the defence of their island fortress. With fighters now depleted to dangerous levels, reinforcements are desperately needed.
As April becomes May the USA comes to Malta’s aid, USS Wasp successfully delivers 2 cargoes of Spitfires and their pilots.
May 1942: General Lord Gort replaces Sir William Dobbie as Governor and Commander-in-Chief, he brings in his hands the George Cross medal and citation from the King.
June 1942: The new fighters take immediate effect in improving the defences but food and supplies continue to deteriorate. Single-ship deliveries by fast warship and submarines cannot keep up. In North Africa, the axis retake most of the coast of Libya and fears of an airborne invasion become acute.
July 1942: The axis, encouraged by their advance in North Africa and the success of their air raids on Malta opt to press on to Egypt, invasion fears recede. Fuel and ammunition stocks are critical, food stocks weeks from starvation.
August 1942: With no alternative, Britain recalls all available warships to fight a convoy through to Malta. 14 of the fastest merchant vessels are committed to Operation Pedestal. They are escorted by the heaviest concentration of warships in the war so far. For 5 days, the convoy is continuously attacked. The attrition is horrific, but finally the 4 surviving merchantmen are delivered to Malta. The new American-built tanker, Ohio, decks awash, engines wrecked, bombed, torpodoed, a crashed axis plane burning on her deck is, by a miracle, brought into Grand Harbour on the 15th of the month, the Feast of Santa Maria. All of her 11,000 tonnes of fuel are intact. The entire population watch as their salvation is nursed home by two small destroyers. The tide of the Siege, and history, was turning.
September 1942: Malta striking forces again press home their interdiction of axis convoys. Air defence goes on the attack seeking raiders before they reach Malta skies.
October 1942: In a 4-day onslaught the axis lose 114 aircraft to 25 Spitfires. Axis losses now total 1,252 with another 1,151 unconfirmed. The civilian population has lost 1,600 killed and 1,818 grievously wounded.
November 1942: Axis forces retreat in North Africa, allied landings take place, leading to their eventual rout. A convoy arrives unmolested. The siege is finally over.
December 1942: Malta becomes the forward base for the first steps in the liberation of Europe. Allied and Commonwealth troops begin to build up in Malta with supplies arriving unhindered.
On the 10th of July 1943 the invasions of Europe begins in Sicily.