Operation Basalt was a small raid. Twelve men from No. 62 Commando, also known as the Small Scale Raiding Force, and No. 12 Commando, under the broader command of the Special Operations Executive, left Portland on the motor torpedo boat MTB 344 at seven in the evening. Their objectives were modest by the standards of larger commando operations: offensive reconnaissance, and the capture of prisoners. The Channel Islands were the only British territory the Germans held, and prisoners taken from there would be intelligence gold, men who knew the garrison's strength, equipment, supply lines, and morale. The raid was led by Major Geoffrey Appleyard, a highly decorated officer who had been in and out of occupied France throughout 1942 on SSRF missions.

They climbed the Hog's Back without being spotted. No sentries challenged them. No patrols crossed their path. At the top they came upon the house of Mrs Frances Noel Pittard, a Sark resident living through the occupation. The commandos broke in. Mrs Pittard, faced with armed British soldiers in her parlor on an island where any contact with the Allies could mean prison or death, did not panic. She told them what she knew. About twenty Germans were quartered in an annex of the nearby Dixcart Hotel. She provided local newspapers from Guernsey, useful intelligence on German administrative policies in the Channel Islands. The commandos offered to take her back to England. She declined. The raiders, with intelligence in hand and prisoners still to find, moved on toward the Dixcart Hotel annex.

What happened at the annex remains partly disputed. The commandos surprised five German soldiers in their quarters, took them prisoner, and bound their hands as the raiding force prepared to march them back to the cliff and down to MTB 344. The German account, supported by some British evidence, is that several of the bound prisoners were killed during the withdrawal, either while trying to escape, or by deliberate British action when escape risked compromising the raid. One German was brought back to England as a prisoner. The others, including the dead, were found by the German garrison the next morning, still in their bonds. The discovery of bound prisoners shot dead would be the detail that mattered most for what came next, both for Allied commandos captured anywhere in Europe over the rest of the war, and for the people of Sark themselves.

On 18 October 1942, two weeks after the raid, Hitler issued his Commando Order. It instructed German forces that all captured Allied commandos, or troops engaged in commando-type operations, were to be executed immediately, regardless of whether they were in uniform, whether they were armed, or whether they had surrendered. The order was a direct violation of the Geneva Conventions. It was carried out repeatedly across Europe over the next three years, producing a string of war crimes for which senior German officers were tried and convicted after the war. Operation Basalt is widely cited as one of the immediate triggers for the Commando Order, particularly the binding of prisoners and the accounts of what happened to them. On Sark itself, the occupation tightened. Mrs Pittard, the woman who had refused to come home with the commandos, was arrested, interrogated, and deported to a civilian internment camp on the continent. She survived the war. The three German soldiers who died on the cliff did not. The British soldiers who killed them carried that night with them for the rest of their lives. The Commando Order outlived all of them.