The occupation of Cecil Island (31 January 1944) was one of the first steps in the invasion of Kwajalein Atoll in the Marshall Islands, and was achieved only after a false landing on the wrong island (Operation Flintlock).
Cecil Island (Ninni) was to be occupied in order to secure Cecil Pass, the best deep water route into the middle of the atoll. It was located to the north-west of the pass, and was the fourth island to the west of the main Kwajalein Island.
Cecil Island was to be attacked by a provisional unit made up of the HQ platoon from 7th Cavalry Reconnaissance Troop and 61 men from Company B, 111th Infantry, before dawn on D-Day. The troops were to be landed from USS Overton (APD-23) and ideally occupy the island before the Japanese elsewhere could react.
When the Overton was around 2,600 yards from Cecil Island, the troops set off in their small boats. The reconnaissance troops went first, in one motor launch and several rubber boats. The infantry followed in Higgins boats. The plan was for the motor launch to tow the rubber boats to within 800 yards of the shore. A powered raft would then take a two man team to the shore, where they would set up lights to guide in the recon squadron. They would establish a beachhead and then summon the infantry. The infantry would then hold the beach while the reconnaissance platoons would search the rest of the island.
The landing didn't go according to plan. The boats were released at 0430 into strong current. They made an un-opposing landing on an island at 0545, and the infantry then followed in. The reconnaissance troop then carried out a brief sweep in which they killed four and captured two Japanese soldiers, but it soon became clear that they had landed on the wrong island - Chauncey, the next island to the north-west, and not located next to the crucial Cecil Pass. At 0810 the troops were ordered to move over to the correct island. Some of the infantry was left to guard Chauncey Island.
The landing part reached Cecil Island fairly easy. This time there was no resistance, and the island was declared to be secure by 1235. This allowed American minesweepers to clear Cecil Pass, ready for the main landing of 1 February.