"The battle of Roi (1 February 1944) saw the US marines captured the main Japanese airbase in Kwajalein Atoll in a single day, after the Japanese defences were almost destroyed by the pre-invasion bombardment.
Roi and Namur were to be attacked by the Northern Attack Force (Task Force 53) under Rear Admiral Richard L. Conolly and the Northern Landing Force, made up of the 4th Marine Division (Major General Harry Schmidt). Admiral Conolly commanded the invasion from the command ship USS Appalachian.
Admiral Conolly's attack force consisted of three old battleships, 2 heavy cruisers, 2 light cruisers 10 destroyers, 2 high speed transports (APDs), 3 escort carriers, 12 LCIs and 4 mine sweepers.
Roi Island was almost clear of ground cover, as it contained the biggest Japanese airfield in the atoll, with three runways, four turning circles, two service aprons, two hangers, thirty revetments and a control tower. The island is 1,250 yards north-south and 1,200 yards east-west. The airfield on Roi was the HQ of all Japanese air power in the Gilberts and Marshalls.
Roi and Namur were connected by a beach on the lagoon side and a causeway half way between the atoll and the ocean. The ocean side was unsuitable for landings, but at high tide the reefs on the lagoon side were under water.
The plan was to capture a number of outlying islands on D-Day, then invade Roi and Namur from the lagoon side on D+1 (1 February 1944). Roi was to be attacked by the 23rd Regimental Combat Team, which was to land two regiments side by side on Red Beaches 2 and 3. A wave of LCI(G)s and armoured LVTs would lead the way, with the troops following in amphibious tractor.
On 29 January TG 58.2 (Essex, Intrepid and Cabot) attacked Roi-Namur, where the Japanese still had 92 aircraft. The carrier attack quickly eliminated the threat, and no Japanese aircraft were in the air after 0800. The same group attacked again on 30 January."