Though not a Coast Artillery unit, the 4th Marines became such an integral part of the coastal defense of Corregidor and Subic Bays, we have included them with this site.

The 4th Marine Regiment was first activated in April 1914 as part of the Marine Corps' Advances Base Force. The regiment was deployed to the Dominican Republic the following year for a peacekeeping duty that lasted ten years. The 4th Marines were reassigned to San Diego in 1924. Two years later, the regiment was assigned to mail guard duty in the western United States. In early 1927, it sailed for Shanghai. Their principal mission: to protect American lives and property. Despite periodic outbreaks of internal disorder, most of the 4th Marines' 14-year tour in China was a relatively peaceful garrison duty.

Although fighting in the area had ceased, tensions in the International Settlement did not fully subside. Japan, with its jurisdiction of territory adjacent to the city now assured, began a campaign to undermine the position of the Western Powers in the International Settlement. The main concern of the 4th Marines thus became one of the thwarting any Japanese attempt to change to status quo of the American sector. A Japanese move in this direction would probably result in little or no assistance to the 4th Marines from the other foreign military contingents, because of their reduction in strength. The situation became more dubious and uncertain with the outbreak of war in Europe in 1939. The value of Italian troops in preserving the integrity of the zone was doubtful because of Italy's membership along with Japan in the Axis alliance. The summer of 1940 saw a worsening of conditions as Italy was now involved in a shooting war with Great Britain and France. In Shanghai as the French garrison on orders from the Vichy Government was neutralized from use in opposition to the Japanese. Two months later Britain withdrew her forces because of pressing needs elsewhere. The 4th Marines, therefore, became the only obstacle in Japan's designs on the International Settlement.

The United States seriously began considering the evacuation of its forces from China following the growth of Japanese power and hegemony in the country. Admiral Thomas C. Hart, commander in chief of the Asiatic Fleet, felt that war was inevitable and began pulling out those units under his command that were in exposed positions along the Chinese coast. He also recommended that the 4th Marines be withdrawn from Shanghai but no action was taken on this suggestion. By September 1941, conditions in China were so grave that officials in Shanghai strongly urged the evacuation of all naval personnel from north China, including the 4th marines. Information had been obtained indicating the Japanese military intended within a short time to seize the entire International Settlement. Incidents were planned by the Japanese so as to give them an excuse to move troops into the American sector. The regiment was placed on alert and ordered to watch for terrorists.

Washington finally consented to the withdrawal of the 4th Marines in the fall because of the increasingly perilous situation and the untenable position of the regiment. Permission for the evacuation was received on 10 November 1941. Plans for its departure that had been drawn up previously were immediately put into effect. The first contingent, consisting of the 1st Battalion and part of the Headquarters, embarked on the newly arrived PRESIDENT MADISON and sailed for the Philippines 17 days, 28 November, the rest of the regiment boarded the PRESIDENT HARRISON and also sailed for the Philippines. The era of the "China Marines" thus came to an end.

The first echelon arrived at Subic Bay on 30 November, followed the next day by the second. The regiment, shortly after the completion of its transfer to the Philippines, was given the responsibility of protecting the Olongapo Naval Station and the naval base at Mariveles. With war immediately on the horizon, the 4th Marines began frantic preparations to make itself ready for that possibility. Although war was expected, it broke out earlier than had been anticipated. Japan launched a sneak attack on the Philippines on 8 December 1941 to coincide with its strike at Pearl Harbor. These attacks, initially, were in the form of bombing and strafing runs on American installations. It was not until four days after the beginning of hostilities that the regiment first engaged the Japanese. Enemy planes made their first attack on Olongapo on the 12th and were met by fire from the Marines' rifles and .30 caliber machine guns, the only weapons available to the regiment.

While air raids against Olongapo continued, the Japanese pressed forward with a ground attack on Manila. They originally landed on Luzon on the 10th. A major assault occurred 12 days later when the enemy came ashore in the Lingayen Gulf area. Manila's capture appeared inevitable. When the enemy neared the city the 4th Marines, now under Army control, was ordered to evacuate its positions at Olongapo. Christmas Eve witnessed the beginning of the destruction of all installations and the withdrawal to Mariveles where the 1st Battalion had been deployed since 8 December. The regiment's move to Mariveles was subsequently followed by its transfer to Corregidor, the island fortress off the southern tip of Bataan. The Marines were immediately given the task of preparing beach defenses on the island, a mission originally entrusted to the Army. As the enemy bombed Corregidor, the Marines worked day and night on strengthening its defensive installations. Antiboat booms were constructed, mines laid, tank traps and trenches dug, and barbed wire strung at potential landing sites.

Once the war had started the regiment's composition and structure was altered. The regiment, which had been understrength for some time, was greatly increased in size. The Marine Barracks at Olongapo was deactivated and its personnel were transferred to the 4th Marines on the 22d of December. The regiment was again reinforced the day after Christmas by the arrival of the 1st Separate Battalion which had been guarding Cavite. This battalion was redesignated as the 3d Battalion, 4th Marines, making the regiment a three-battalion-size organization for the first time in seven years. It continued to expand in size over the next four months, thus becoming one of the strangest military organizations in Marine Corps history. Most of the additional personnel came from the Army, Navy, and Philippine units. Members of the strengthened 4th Marines represented all segments of U. S. and Philippine military services. The regiment by mid-April 1942 had increased in size to five battalions. The Reserve Battalion was activated on 19 February and the 4th Battalion was activated on 9 April. This latter battalion was composed almost entirely of Navy personnel.

As the weeks passed, the 4th Marines and other units garrisoning Corregidor realized the hopelessness of the situation when it became clear that no relief force would be forthcoming. The 4th Marines' mission of defending the beaches gained new importance as the Japanese moved down the Bataan Peninsula. Originally, the beach defenses were assigned as follows: the 1st Battalion maintained the eastern sector of the island which included the important Malinta Hill complex, the site of General Douglas MacArthur's headquarters and later Lieutenant General Jonathan M. Wainwright's headquarters for U. S. forces in the Philippines; the 3d Battalion was entrusted with the middle sector; and the 2d Battalion held the western sector. Headquarters and Service Companies functioned in the beginning as a general reserve. The activation of two more battalions strengthened the regiment's defensive position. The general reserve, which was composed mainly of personnel from the Headquarters and Service Companies, was reorganized in February. New personnel were added to this force and it became the Reserve Battalion. This battalion and 4/4 were subsequently employed as a regimental reserve.

On Bataan, American and Philippine forces were valiantly trying to stem the Japanese tide that was sweeping down the peninsula. The inevitability of defeat, however, was more than apparent by the beginning of April. American commanders, feeling that further resistance was useless in the face of the continued enemy offensive, surrendered their forces on 9 April. Only a small percentage of the defenders of Bataan managed to escape to Corregidor. Among these were a few members of the 4th Marines who had been previously detached in January for service on Bataan. The fall of the peninsula now brought new pressures to bear on Corregidor. For months it had been subjected to repeated enemy air strikes. The Japanese, with Bataan secured, not only stepped up these attacks but brought in artillery and subjected the isolated American bastion to a heavy bombardment. A virtual rain of shells and bombs saturated the island during April, resulting in the destruction of most beach defenses. The likelihood of an amphibious assault became much more pronounced by May.

Following an unusually heavy bombardment, Japanese landing craft began moving toward Corregidor on the evening of 5 May 1942. The enemy made his first landing at 2300 on North Point, followed by further landings to the west of the Point; all took place in 1/4's sector. Despite heavy resistance by the battalion and severe losses to the Japanese, the enemy was able to acquire a toehold on the island. The 1st Battalion doggedly resisted the advance; nonetheless, the Japanese were able to push forward, severing communications within the area and cutting off elements of the battalion from those positions defending Malinta Hill. The Reserve Battalion, as a result, was ordered to the area to aid the beleagured 1st Battalion. The Reserve Battalion, after moving up to the line of battle, launched three unsuccessful counterattacks. All took place in the area around Denver Battery, a strategic American antiaircraft gun position which stood on high ground south of Cavalry Point and which had been overrun by the enemy. Colonel Samuel L. Howard, the 4th Marines' commanding officer, committed the 4th Battalion to the battle following the failure of the first three assaults. Another counterattack was launched at daybreak; this time it was spearheaded by 4/4. The attack at first gained some ground but stalled when the Japanese began landing tanks on the beachhead. Once the American attack had faltered the Japanese unleashed a terrific artillery bombardment on the Marines' lines from nearby Bataan.

The situation grew more perilous for the Marines by mid-morning, although 2/4 and 3/4 had not yet been committed. Concern over possible new landings in other areas prescribed the necessity of maintaining these units in their positions and not employing them in the battle. No major landings, however, occurred that morning; the Japanese instead concentrated on expanding the beachhead that had already been seized. The enemy continued to push towards Malinta Hill; General Wainwright's headquarters was in jeopardy. The situation grew worse when it was learned that the Marine defenders' ammunition was almost exhausted and all their heavy guns had been destroyed. Feeling that further resistance was useless and fearing a possible massacre of 1,000 sick and wounded personnel in Malinta Tunnel, General Wainwright decided to surrender. At 1200 the surrender went into effect. Isolated pockets of Marines, however, continued fighting for four more hours until the surrender order reached them. Colonel Howard, in the meantime, ordered the national and regimental colors of the 4th Marines burned to prevent their capture. He then led his men into captivity. As of noon on 6 May 1942, the 4th Marines temporarily ceased to exist.