The Palau Islands were an important part of Japan's inner defense line which flanked the American thrust towards the Philippines. Plans for the seizure and occupation of the Palaus were made in March 1944 to be executed in September.

The expeditionary force for Operation STALEMATE, as the Palaus operation was to be known, was composed of two divisions of the III Amphibious Corps, under the command of Major General Roy S. Geiger, USMC. The 1st Marine Division was given the task of seizing the main island of Peleliu and its airfield and the Army's 81st Infantry Division would secure the smaller island, Angaur, south of Peleliu.

Peleliu was dominated by a long precipitous ridge called the "Umurbrogol," honeycombed with caves and masked by dense jungle growth. A coral reef, intermittently backed by mangrove swamps, ringed the entire island. These features were very effectively utilized by the Japanese in constructing exits, fire ports, and artillery positions through a network of caves and tunnels.

Colonel Kunio Nakagawa commanded the tactical defense of Peleliu, despite the presence of other more senior officers. The island defenders numbered about 10,700, divided equally between the Army and Navy. The Army force consisted of five infantry battalions supported by artillery and tanks taken from the 14th Division, one of Japan's finest units. The Navy units were composed of 800-1,000 combat troops of the 45th Guard Force Detachment and antiaircraft units, and about 2,000-2,200 men belonging to naval construction battalions. The overall defensive concept was devised by Lieutenant General Sadae Inoue, garrison commander of the Palaus. It called for the Japanese to entrench themselves deep, hold fire during the initial attack, and then while holding the Umurbrogol as the anchor position counterattack and infiltrate when advantageous.

Marine planning called for extensive pre-landing bombardment followed by the landing of all three regiments of the 1st Marine Division abreast over five beaches on the southwest shore of Peleliu. The 7th Marines, 'Less one battalion in reserve, was to land in the south, isolating the southern tip. The 5th Marines, landing in the center, was given the mission of capturing the airfield. The 1st Marines, landing to the north, was to execute a movement to the left and attack the long axis of the island.

On the 12th of September, three days before the landing, naval gunfire support ships and planes from four escort carriers began bombarding the Japanese positions. Beset by ammunition shortages, lack of sufficient naval gunfire spotters, and poor aerial reconnaissance coverage the pre-invasion strikes proved inadequate, as the 1st Marine Division was soon to find out.

Shortly after daybreak on 15 September as the amphibian tractors crossed the reef, mortar and artillery fire rained down and it became evident that the pre-invasion bombardment had accomplished little. On the right, the 7th Marines met a veritable beehive of untouched defenses. In the center, the 5th Marines had it easier for it advanced across the southern end of the airfield with relative ease. By nightfall of that first day it had firmly established itself in strong positions clear across the island.

It was the 1st Marines, on the left, which had the hardest going. Undetected obstacles lay immediately in their path, and, on the left a fortified position extended from the beach. Reduction of this position cost the assault company two-thirds of its complement and the survivors of the assault were cut off for 30 hours by fierce Japanese counterattacks.

Colonel Nakagawa launched his first major counterattack on the afternoon of D-Day. This was a well planned and executed tank/infantry thrust across the airfield at the boundary between the 1st and 5th Marines. Almost as suddenly as it began the Japanese thrust ended, leaving all but two of the supporting tanks as crumpled tin cans behind the Leatherneck lines. Other lesser attacks were mounted, but all failed. Nevertheless, as night fell the division held less than half of its D-Day objectives, and those precariously. Artillery and tanks had been put ashore and an advance division command post had been established, but premature commitment of some elements had reduced the division reserve to one battalion. By the end of this first day, 210 Marines had lost their lives and 901 had been wounded. D-Day was a fair indication of what was to come.

The succeeding week saw the 7th Marines, less one battalion, systematically reduce enemy defenses on the southern end of the island. The 5th Marines overran the airfield and the northeastern end of the island. It was in the 1st Marine zone of operations that the hardest fighting was to occur. Colonel Lewis B. Puller's 1st Marines with its attached battalion from the 7th Marines, was ordered to reduce the Umurbrogol hill mass. It was here that the enemy-infested caves introduced such names as the Horseshoe, Death Valley, and Walt's Ridge into the annals of Marine Corps history. Typical of the stiff fighting for the Umurbrogol was the 19 September attack on Walt Ridge (as it was to be called) undertaken by Captain Everett P. Pope's "Charlie" Company, 1st Marines. Jumping off with 90 men Captain Pope led his command across a fire-swept causeway, through a swamp, and with a rush pushed the company atop a hill which proved not to be a hill, but a long coral ridge exposed to severe flanking fire. Charlie Company couldn't penetrate the coral to dig foxholes and as a result was mercilessly pounded by enemy fire. By nightfall the company strength was down to 15 men and the captain. All night they held, repulsing the final enemy charge with chunks of coral. Finally the survivors were ordered off the ridge. For this night's work, Captain Pope received one of the Medals of Honor awarded to men of the division on this coral island. It would take another two weeks to seize and hold the position

The 1st Marines, after a week of such effort was finished as an effective unit and was withdrawn. The 7th Marines which relieved Colonel Puller's Regiment continued the grind against the Umurbrogol pocket.

On 20 September, the battered 1st Marine Division was joined by the Army's 321st Infantry Regiment (a component of the 81st Infantry Division) which had taken part in the three-day seizure of Angaur--the other phase of the Palaus operation. The 321st was a blooded, capable regiment, and more important, was fresh. With its arrival things began to look up. The soldiers advanced north up the west road covered on one flank by a battalion of the 7th Marines and shadowed on the other by the heights of the Umurbrogol. At the upper end of this advance they swung east across the island, while the 5th Marines continued moving to its northern end.

Once in the north, the 5th Marines fought and secured the Amiangal, a ridge slightly less formidable than the Umurbrogol. On 28 September, the 3d Battalion, 5th Marines took Ngesebus Island just off Peleliu's northern end.

With the reduction of the Amiangal and the seizure of Ngesebus, the Japanese resistance was concentrated in the Umurbrogol Pocket, which took eight more weeks of hard fighting to reduce.

On 16 October, almost-exactly a month after the initial assault, the Marines were relieved and the final reduction of Peleliu was assigned to the 81st Infantry Division. In the meantime, Marine air had arrived on the island and was utilizing the air base not only in support of operations on Peleliu, but as the base for the air defense of the massive new fleet anchorage at nearby Ulithi.

Finally on 25 November, the 81st Division overcame the last enemy resistance in the Umurbrogol, and Peleliu was in American hands. The tally sheet at the end of two-months' fierce fighting revealed 8 Marines awarded the Medal of Honor for this campaign, and 1,252 Marines killed and 5,274 wounded, while Army losses were 542 killed and 2,736 wounded. Almost the entire Japanese garrison was wiped out; only 302 men were captured.