The original plan had been for the raid to be carried out on the night of 12/13 July, however, at the last moment, it was put back to 14/15 July. Even then, shortly before embarkation, Durnford-Slater received intelligence that the Germans had reinforced a number of the places where it had been planned to land some of the parties and as such the plan was changed at the last moment. After the details were worked out, final battle preparations were undertaken in the gymnasium at the Royal Naval College, Dartmouth where some of the cadets helped the commandos with loading magazines and helping prepare the Bren guns and Thompson sub-machine guns that had been brought down from London specifically for the operation.
At 17:45 the raiding force embarked upon the two destroyers, HMS Scimitar and HMS Saladin and accompanied by six Royal Air Force air-sea rescue launches, who would take them from the destroyers to the landing beaches, they set out for the island of Guernsey. Due to the loud noise of the engines of the RAF launches, it was arranged that RAF Avro Ansons would fly over the island to disguise the sound of the engines.
Under the plan that Durnford-Slater had worked out, he had the troops from the independent company attacking the airfield, while the commandos were to create a diversion. To this end, three landing points were selected; however, in the end only the diversionary force from No.3 Commando, consisting of only 40 men, was able to land successfully, landing at a beach in Telegraph Bay just west of the Jerbourg Peninsula ata 00:50 on 15 July, despite a faulty compass on the launch.
One party of No.11 were taken to the wrong island (Sark) as a result of another faulty compass, landing on Little Sark the team explored La Sablonnerie and not finding any Germans returned safely to the destroyer. Another party crashed into a rock and the other two launches broke down after experiencing a series of technical problems.
Although they managed to get ashore—albeit soaking wet—the party from No. 3 Commando failed to find any of the 469-man German garrisons. Despite locating a German barracks and a machine gun nest, both had been abandoned prior to their arrival. One islander was encountered only as he had a speech impediment, he was knocked out to keep him quiet. They demolished a loose garden wall to make a small roadblock. Not hearing any noise from the direction of the airport, they decided to quietly retreat. The rendezvous with the destroyers that were picking them up was at 03:00 and if they were late the destroyers were under orders to leave them behind, so the party subsequently returned to the beach, stopping to cut a couple of telegraph lines on the way. Upon arriving at the landing beach, the raiders discovered that they had to extract themselves by swimming some 100 yards (91 m) out to their boats as the tide had risen too high for their motor craft to beach among the rocks
At this stage, it was discovered that three of the men from 'H' Troop, No. 3 Commando could not swim and had to be left on the beach with additional French currency. Although Durnford-Slater requested that a submarine is sent back for these men, the Admiralty decided that it could not take the risk and as a result of the men later surrendered. During the extraction, a dinghy was used to ferry weapons to the boats, but on the fifth excursion it was dashed against a rock and overturned. One of the boat's two occupants, a soldier, was presumed drowned at the time, although later it was reported that he actually managed to get ashore and was subsequently captured.