The occupation of Chauncey Island (31 January-2 February 1944) began with an accidental landing on the island at the start of the invasion of Kwajalein, and was completed two days later.
Chauncey Island was the fifth island to the west of the main Kwajalein Island. It wasn't actually an American target for the first day of the operations, but its neighbour, Cecil Island, was. The plan was for a 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 (DD-239/ APD-23) and ideally occupy the island before the Japanese elsewhere could react.
The unit left its ships at 0430 on 31 January 1944, but a strong current and an offshore wind caused problems finding their island. The original plan had been for the reconnaissance troops (in rubber boats) to be towed to within 800 yards of the shore by a motor launch. Two men on a powered raft would reconnoitre the beach and guide in the reconnaissance troops. They would secure the beach, and summon the infantry. The rubber boats were released too soon, and had to be recalled, but even so the unit had landed at 0545. A beachhead was established, and a short patrol found six Japanese troops, killing four and capturing two.
At this point it became clear that the Americans had landed on Chauncey Island instead of Cecil Island. At 0810 they were ordered to leave Chauncey and continue on to Cecil. At this point the force split. Part of the infantry was left on Chauncey to watch a beached tugboat, while the rest of the force successfully occupied Cecil Island.
The troops left on Chauncey were made up of Company B, 111th Infantry, under Captain Gilbert Drexel. During a patrol of the island his men ran into an unexpectedly strong force of around 100 Japanese near the centre of the island. At the same time the troops watching the tugboat came under fire from with the boat. The Overton opened fire on the tugboat.
Although the 111th were probably having the best of the battle, losing two men but estimating that they'd killed 45 Japanese troops, they were ordered to move to the more important Cecil Island. One squadron of infantry and a party of crew from the Overton were left to guard the tug, while the rest of the infantry moved across to Cecil.
On 1 February another platoon of US troops landed on the island, and set up a defensive perimeter. Later in the day it was decided to complete the occupation of the island, and early on 2 February the 7th Reconnaissance Troop landing at the north-western corner of the island. Once the troops were onshore they set up four 60mm mortars and bombarded the island, aided by gunfire from USS Overton. Three platoons then advanced side-by-side across the island, eventually finding the Japanese defenders in a trench near a long earth mound. The platoons attacked from the front and both sides, but the Japanese held out for 45 minutes, and the defenders were only defeated after a bazooka rocket detonated inside their position. This was the only significant fighting on the island, and by the end of the day it had been secured.