The 'Raid on Santorini' was a British and allied undertaking by the Special Boat Service against the mixed German and Italian garrison of the island of Santorini (formally Thera) in the Aegean Sea (24 April 1944).

The raid was made in tandem with similar operations on the islands of Ios, Mykonos and Amorgos with the object of destroying Axis naval observation posts and radio stations on the islands of the Cyclades group.

During the winter of 1943/44, the Germans had secured control of the islands of the various Aegean Sea archipelagos, and in the spring of 1944 still maintained appreciable garrisons on many Greek isles. The British wished to maintain a secondary front in the Aegean Sea despite their defeats on Kos to the German 'Eisbär' and Léros in the German 'Leopard' (iii), the Middle East Headquarters issued orders to the Special Boat Service special forces unit to attack the garrisons of occupied Greek islands such as Santorini.

On 19 April, a small forces of 19 commandos under the command of Major Anders Lassen sailed from the SBS’s secret base in Balisu bay, on the coast of Turkey, on board a pair of schooners. After a three-day voyage that included intermediate stops in Syrna and Anydros, the group landed on an easterly beach near cape Columbo on the night of 22/23 April. The group marched toward the village of Vourvoulos and after contacting member of the local population. hid in a nearby cave. The two schooners sought shelter in the nearby Christiana islands, to the south-west of Santorini. One member of the group of commandos was a Greek, Lieutenant Stephanos Kasoulis who, on 23 April, was guided by locals to Fira, the island’s main settlement, to gather intelligence. On the basis of the information garnered by Kasoulis, Lassen decided to divide his force into three detachments: the first was to attack the barracks in Fira; the second was to head to the residence of Leutnant Hesse, the German commanding officer, in Fira and attempt to capture him; and the third was to hit the radio station in Imerovigli. This last’s radio had a long range and served as a relay supporting communications between Athens and Crete.

The attack was scheduled for 00.45 on 24 April, and the three detachments were led to their targets by local guides. The barracks were located in the centre of Fira, on the second floor of a building that housed a bank. The attackers came from two directions and, in spite of the barking of dogs, the Special Boat Service party managed to surprise the 40-strong garrison and kill most of them. During the attack, Kasoulis was shot in the chest and died immediately. Sergeant Frank Kingston was shot in the abdomen and died of his wound a few hours later. The attack on Hesse was unsuccessful as he and a few others managed to escape unscathed. The building housing the radio installation was blown up with time bombs. The commandos then escaped in their two schooners, taking with them some of the locals who had helped them.

On 29 April, German reinforcements from the island of Mílos surrounded Vourvoulos, seized all local males aged 14 years and older, and threatened them with reprisals if they did not reveal the identities of any persons who helped the commandos. A few villagers admitted their involvement and were executed by firing squad. In all, a total of five men, among them the village’s mayor, were killed. It is unclear why the rest of the villagers and the village itself were spared. It has been claimed that this was the result of a letter written to Hesse by Lassen, warning him that his name was known to the Allies who would hold him accountable for any reprisals he ordered.

In overall terms, therefore, two commandos died in the operation and five civilians were shot in reprisal. Another 13 civilians from Imerovigli, who were hoping to seize German provisions in the radio building, died when the building was destroyed by explosives. The number of German casualties was around 40 and 19 were taken prisoners. This and similar operations forced Generalleutnant Ulrich Kleemann, commander of the Sturmdivision 'Rhodos', to remind his men that they were living in an enemy country' and to reinforce the Aegean Sea island garrisons by 4,000 men. These forces remained tied down in place for the rest of the war.