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Operation Forager: The Battle of Saipan 

15 June–9 July 1944 

Saipan Invasion, June 1944.

Saipan, June 1944: Naval bombardment in support of U.S. Marine Corps ground operations. Note the extensive cultivated areas (80-G-238385). 


When it happened, in June and July 1944, the conquest of Saipan became the most daring—and disturbing—operation in the U.S. war against Japan to date.1 And when it was over, the United States held islands that could place B-29 bombers within range of Tokyo.

Since the fall of the Marshall Islands to the Americans a few months earlier, both sides began to prepare for an American onslaught against the Marianas and Saipan in particular. The Americans decided that the best course of action was to invade Saipan first, then Tinian and Guam. They set D-day for 15 June, when Navy Sailors would deliver Marines and Soldiers to Saipan’s rugged, heavily fortified shores.

The Navy’s involvement bookended the operation: naval vessels and personnel ferried Marines and Soldiers to the beaches and then, after ground combat was over, took leading positions in the administration of the occupation.


The logistical demands of the invasion of Saipan were dizzying. Planners had to see to it that 59 troopships and 64 LSTs could land three divisions’ worth of men and equipment on an island 2,400 miles from the base at Guadalcanal and 3,500 miles from Pearl Harbor.2 These challenges aside, Navy, Marine Corps, and Army leadership anticipated a quick campaign based on intelligence they were receiving about enemy troop levels on Saipan.

American personnel in Hawaii ran their final rehearsals in May.3 Unfortunately, the Marines and Army had conducted most of their training separately. The results: conflicting tactics, conflicting expectations, and serious confusion.4

Adding to the complexity of the operation, a sizeable Japanese population lived on Saipan. The invasion would be the Americans’ first encounter of this kind, which meant that the action would entail new dangers and dreadful responsibilities. In preparation, troops received training in rudimentary Japanese.5

Preparatory Activities

Air raids began in February 1944, when the Navy’s Fast Carrier Force destroyed some of the island’s docks. “That area was all in flames because the Japanese had a lot of storage tanks there,” remembers Marie Soledad Castro, then a young girl resident on Saipan and whose father was a dockworker.6 The raids continued. “One of my older brothers, Shiuichi, was killed during one of these air raids,” reports Vicky Vaughan. “We never found his body,” she continues; “like so many, he just disappeared.”7

In May, there were strikes on Marcus and Wake Islands to secure the approach to Saipan. By 8 June, a great assemblage of Navy ships arrived in the Marianas region from various points in the east, from Majuro in the Marshalls to Pearl Harbor in Hawaii.8

Having hobbled Japanese air forces in the region by 11 June and, in the two days before D-Day, bombarded Saipan’s coasts, conducted risky but invaluable reconnaissance, and blown up parts of the coastal reefs, the Navy was now ready to land American personnel on the island.9

Initial Landings

Before dawn on D-day, 15 June, Sailors prepared a grand breakfast for the Marines of the 2nd and 4th Divisions, and then it was time to board the amphibian tractors.10

Fifty-six of these vehicles proceeded in lines of four toward the eight beaches that had to be stormed. Thirty-thousand Japanese personnel, with their artillery, held their fire as the tractors gained the reefs and arrived in the lagoon.11

And then, with a deafening roar of Japanese artillery, it became clear that the preparatory bombardment of the shoreline defenses, which had started at dawn, had not done enough.12 These installations were hidden well in Saipan’s coastal topography, which featured high ground within range of the lagoon and the reefs, a natural obstacle to U.S. vessels and a natural focal point for Japanese fire.13

Deadly complications besieged U.S. forces all at once. The intensity of the enemy’s fire resulted in one area becoming overcrowded with Marines trying to get a footing on shore. This mass of U.S. personnel became an easy target for mortars and other projectiles.14 Nevertheless, the Marine divisions managed to get to dry ground before H-hour had passed.15

Then came another nasty surprise. The amphibian tractors were not functioning as planned. Their armor was not heavy enough to withstand the barrage from Japanese artillery, and their agility on rough ground proved lacking.16 Troops scattered in several directions as hilltop snipers tried to pick them off one by one. Of the four commanders of the 2nd Marine Division’s initial assault battalion, none escaped this phase of the battle unharmed.17

Eventually, troops and their officers reestablished order and proceeded apace.

Landings continued into the night. USS Twining (DD-540), on patrol in the channel between Saipan and Tinian, afforded its Sailors a “nightmarish” perspective on the beaches. “We were close,” Lieutenant William VanDusen remembers: “Heavier ships were firing over our heads onto the beach. There were flares being dropped by Japanese planes.” Earlier that day, Twining had added to the melee when her guns “hit a large ammunition dump” on shore, as VanDusen describes it. The facility “exploded with a tremendous cloud of smoke and flame.”18

Japanese resistance proved far greater than anticipated, not least of all because the latest intelligence reports had underestimated troop levels.19 In reality, troop levels, in excess of 31,000 men, were as much as double the estimates.20 For at least a month, Japanese forces had been fortifying the island and bolstering its forces. Although U.S. submarines had managed to sink most of the transports to Saipan from Manchuria, the majority of these troops survived to supplement a full 13,000 men to the 15,000 or so already on site.21

D-day casualties were high—as many as 3,500 men in the first 24 hours of the invasion but—in spite of these, there were now 20,000 combat-ready troops on shore by sunset with more to come.22 These reinforcements could not arrive too soon, as the Japanese defense doubled down and changed tack by deploying tanks and infantry in the relative darkness of night.23

Conditions improved the following day when the next group of battleships arrived to bombard the coast anew.24 And yet, in the cool light of morning, it became clear that the Marines had not succeeded in reaching their assigned line in the sand. Fortunately for the Americans, the Japanese had not succeeded, either, in their efforts to repulse the invaders.

In the Philippine Sea

At this pivotal juncture in the operation, Lieutenant General Holland M. Smith, USMC (V Amphibious Force commander), Admiral Raymond Spruance (Fifth Fleet commander), and Vice Admiral Richmond Kelly Turner (amphibious and attack forces commander) conferred nearby.25 In response to conditions on the ground, they postponed the invasion of Guam so that the Marine division tasked with conquering it could be diverted to Saipan. They also called in the operation’s reserves, the Army’s 27th Infantry Division.26

The unexpected difficulties on the beaches also prompted Admiral Spruance to bolster the naval defense by committing still more ships to the operation. To safeguard this veritable armada, he ordered that transports and supply ships clear the area by nightfall and head east out of harm’s way.27

Spruance had good reason to worry, not necessarily about the beachheads, which appeared to be secure before D-day-plus-1 had ended, but about the First Mobile Fleet of the Imperial Japanese Navy. “The [Japanese] are coming after us,” Spruance said, and they were bringing with them 28 destroyers, 5 battleships, 11 heavy cruisers, 2 light cruisers, and 9 carriers (5 fleet, 4 light) with somewhere near 500 aircraft total.28

The resulting engagement—the Battle of the Philippine Sea of 19–20 June—resulted in a decisive U.S. victory that nearly eliminated Japan’s ability to wage war in the air.

Then it was back to Saipan, where U.S. military personnel still needed reinforcements and materiel.29 Indeed, just hours after the Philippine Sea engagement had ended, the Saipan landings resumed. Attack transport Sheridan (APA-51) was among the first of the ships to return. For days, Sailors had been watching the action on the shore from Sheridan’s decks. This got easier to decipher at dusk when the tracers came out, according to Lieutenant j.g. Harris Martin. The Americans’ flamethrowers, too, shone brightly amid the carnage: “We could see some of our landing craft being hit by Japanese artillery and we watched Japanese tanks as they counterattacked from the low hills”.30

Securing the Interior

The center of Saipan, no more than six or so miles from the farthest coast, is mountainous, but the rest of the island consisted mostly in open farmland, almost all of it planted with sugarcane and therefore inhabited.31 Uncultivated lands—about 30 percent of the island’s surface—featured dense thickets and even denser grasslands. These, plus the fields of sugarcane, made taking and holding ground particularly slow going.32

The population of Saipan was diverse: Japanese colonists mingled and even intermarried with descendants of indigenous islanders, who themselves often descended from German and other European settlers of the pre-Japanese period.33 In 1919, having been lost by the Germans to the Japanese, Saipan fell under a League of Nations mandate to Japan, at which point the Japanese government began to encourage settlement on Saipan’s lucrative, sugarcane-laden soil.

By February 1944, it was obvious even to the island’s children that something terrible was about to happen: “Just before the invasion took place,” remembers one civilian whose girlhood was spent on the island, “several trucks with Japanese soldiers [drove] up to our school, and the next day we had to take our classes under a mango tree. Later, when the bombs began to fall, classes ended for good.”34

The subsequent invasion occasioned a refugee crisis on the island and, soon, some of the most harrowing experiences any civilian would face in the course of the war. Cristino S. Dela Cruz, an islander who later joined the U.S. Marines, remembers the day, on the eve of invasion, when Japanese troops confiscated his family’s house in Garapan. Dela Cruz’s family fled inland, as did so many others, to the apparent safety of an adjacent ridge.

Then the Americans landed nearby, and the Dela Cruz family’s ordeal really began. A hole in the ground provided the only cover. There the family and several others subsisted for a week on rice, coconuts, and a small supply of salted fish as the battle raged around them. Two of the Dela Cruz’s daughters died in a bombing. One of the young sons succumbed to sniper fire just as the family was surrendering to U.S. Marines, who were trying to load everyone onto a truck bound for the relative safety of an American lines.35

Still less fortunate families did not find a cave or a hole in which to hide. As survivor Manuel T. Sablan explains, “We had no shovels, no picks, just a machete, so we cut some wood and used that as picks.”36 Vicky Vaughan and her family did not even get so far as that. They became trapped under their own house until Japanese soldiers, in search of a defensible position, pushed them out into the open. With the battle underway, Vicky watched the grisly deaths of her family members before herself falling victim to the American onslaught: “I felt something hot on my back. They were using flamethrowers, and my back had been burned. I screamed hysterically.”37

To many civilian families, neither surrender nor survival were available. To surrender, a person would have to run into the crossfire, as Vicky’s family discovered. And to do so would expose one to the real danger of murder at the hands of Japanese forces, who forbade surrender on pain of death. Escolastica Tudela Cabrera remembers when Japanese soldiers arrived “at our cave with their big swords and said if anybody went to the Americans, they would cut our throats.”38 Threats like these, which happened in the context of the apparent impossibility of reaching safety, prompted entire families to commit suicide, as U.S. Marines and Soldiers reported.39

Japanese military personnel, too, opted for suicide, rather than face execution at the hands of their own compatriots for attempting to surrender to the Americans.

The worst scenes played out atop the cliffs at the island’s northern tip. “The Japanese [were] jumping from the cliffs at Marpi Point,” remembers Lieutenant VanDusen, who watched the scenes from aboard Twining: “We could see our men in their camouflage uniforms talking to them with loudspeakers, trying to convince them that no harm would come to them, but obviously this was to no avail.”40

The Aftermath

When it was all over, Saipan could be declared secure. The date was 9 July, more than three weeks since the start of the invasion.41 Now began the work of tending and processing the prisoners, both civilian and military.

Lieutenant j.g. Martin, who had landed on D-Day-plus-5, helped set up and administer the island’s internment and displaced persons camp. “The Marines were bringing in prisoners even before we got there,” he says, and in the beginning, “everybody was kept under guard no matter if they were Japanese, Korean, or Chamorros,” the term for indigenous islanders. Eventually, Martin and the others had the idea of separating these groups, not least of all because conflict persisted after years of exploitation by the Japanese. Moreover, the Chamorros, as well as people of mixed ancestry, Japanese troops, and Korean combatants, who had been drafted into the Japanese forces, now held differing legal status with respect to the laws of war and the United States.42 Among their many tasks, Martin and his fellow Navy and Army officers had to distinguish among prisoners, some of whom held more than one status at once.

Meanwhile, Navy civil engineers (Seabees) delineated a plan for the camp and ordered the construction of shelters and other facilities. “They were pretty flimsy buildings,” recalls Martin, with “corrugated tin roofs and . . . open at the sides.”43 Drainage, especially from the privies, was of serious concern.44

An inmate’s experience of Camp Susupe, as it was called, depended largely on his or her ethnicity, gender, and combat status. Antonieta Ada, a girl of mixed Japanese-Chamorro parentage, describes the place as absolutely “awful.” When, finally, her Chamorro father managed to locate Antonieta and have her transferred to his people’s section of the camp, things changed for the young girl: “The Chamorro camp seemed to have better accommodations and better food,” she attests. Antonieta’s Japanese mother was not so fortunate. As a fully Japanese adult civilian, she had to remain in the Japanese section. “I saw my Japanese mother only once after my arrival in Camp Susupe,” says Antonieta. “She was very weak and could hardly talk. She died not long after that.” Antonieta’s brother also had to remain in the Japanese section, which appears to have been the practice in these situations. After the war, he would be forcibly repatriated to Japan.45

Chamorro people with no Japanese family reported a different set of experiences and feelings—primarily relief and even gratitude. “In Camp Susupe,” according to Marie Soledad Castro, “we were so thankful that the Americans came and saved our lives. There was a rumor at that time that the Japanese were going to throw all the Chamorros in a big hole and kill them. We felt that the Americans were God-sent.”46

Wages of War

The invasion of Saipan was horrific. When it ended, at least 23,000 Japanese troops were dead, and more than 1,780 had been captured.47 Nearly 15,000 civilians languished in U.S. custody. Finally, 22,000 Japanese, Okinawans, Koreans, and Chamorro civilians—as well as those of mixed ancestry—had fallen victim to murder, suicide, or the crossfire of battle.48

The Americans suffered 26,000 casualties, 5,000 of which were deaths.49

Yet the American victory was decisive. Japan’s National Defense Zone, demarcated by a line that the Japanese had deemed essential to hold in the effort to stave off U.S. invasion, had been blown open.50 Japan’s access to scarce resources in Southeast Asia was now compromised, and the Caroline and Palau islands now appeared to be ready for the taking.51

As historian Alan J. Levine points out, the capture of the Marianas amounted to a “decisive break-in” on the level of the nearly concurrent Allied breakthrough at Normandy and the Soviet breakthrough in Eastern Europe, which portended the siege of Berlin and the destruction of the Third Reich, Japan’s principal ally.52

The global context of the defeat was not lost on the Japanese command or the Japanese public, but now there were more immediate vulnerabilities to consider.53 On 15 June, the same day as Saipan’s D-day, American forces accomplished the first long-range bombing raid on Japan from bases in China. With Saipan’s airfields soon to be operational (as well as those of Tinian and Guam, which the Americans would surely get in due course) and with Japanese air power having been all but eliminated in the Battle of the Philippine Sea, there was no protecting the home islands from aerial bombardment.54

                                                            —Adam Bisno, PhD, NHHC Communication and Outreach Division, June 2019 


1 Woodburn S. Kirby, The War Against Japan, vol. 3: The Decisive Battles (London: Her Majesty’s Stationery Office, 1961), 431.

2 Waldo Heinrichs and Marc Gallicchio, Implacable Foes: War in the Pacific, 1944–1945 (Oxford: Oxford University Press, 2017), 94. Although bases in the Marshalls lay fewer than 1,500 miles away, the islands’ desolate landscapes could not support any kind of large-scale mustering of men and materiel. Every thing would have to come from great distance over perilous waters. See Kirby, War Against Japan, 431.

3 Gordon L. Rottman, World War II Pacific Island Guide: A Geo-Military Study (Westport, CT: Greenwood, 2002), 378.

4 Harold J. Goldberg, D-Day in the Pacific: The Battle of Saipan (Bloomington, IN: Indiana University Press, 2007), 3.

5 See the oral testimony of Professor Harris Martin, in Saipan: Oral Histories of the Pacific War, compiled and edited by Bruce M. Petty (Jefferson, NC: McFarland, 2002), 157.

6 Oral testimony of Marie Soledad Castro, in Saipan: Oral Histories (op. cit.), 49. Cf. Kirby, War Against Japan, 429.

7 Oral testimony of Vicky Vaughan, in Saipan: Oral Histories (op. cit.), 18. In May, American forces also bombed Marcus and Wake islands, also in the Marianas, to secure the approach to Saipan in June. See Kirby, War Against Japan, 429. 

8 Kirby, War Against Japan, 431; Rottman, World War II, 378.

9 For a vivid and thorough account of the reconnaissance and detonations accomplished by the Underwater Demolition Teams’ swimmers, see Samuel Eliot Morison, History of United States Naval Operations in World War II, vol. 8: New Guinea and the Marianas, March 1944 to August 1944 (Boston: Little, Brown & Co., 1953), 183–84. On preparatory strikes, see Alvin D. Coox, “The Pacific War,” in The Cambridge History of Japan, vol. 6: The Twentieth Century, edited by Peter Duus (Cambridge: Cambridge University Press, 1987), 362; Alan J. Levine, The Pacific War: Japan versus the Allies (Westport, CT: Praeger, 1995), 121; Kirby, War Against Japan, 430–32.

10 Goldberg, D-Day, 3; Heinrichs and Gallicchio, Implacable Foes, 94.

11 Heinrichs and Gallicchio, Implacable Foes, 94–95.

12 Levine, Pacific War, 121; Kirby, War Against Japan, 432. 

13 Heinrichs and Gallicchio, Implacable Foes, 94; Rottman, World War II, 376.

14 Goldberg, D-Day, 3.

15 Kirby, War Against Japan, 432; Rottman, World War II, 378.

16 Levine, Pacific War, 121.

17 As Heinrichs and Gallicchio, Implacable Foes, 95, explain, “Officers rounding up troops” amid the confusion of the landing “made their presence felt and in so doing became targets for snipers.”

18 Oral testimony of William VanDusen, in Saipan: Oral Histories (op. cit.), 162.

19 Levine, Pacific War, 121.

20 According to Heinrichs and Gallicchio, Implacable Foes, 93, the Japanese had 31,629 men on Saipan, 6,160 of whom were Navy combatants.

21 Heinrichs and Gallicchio, Implacable Foes, 93–94.

22 Heinrichs and Gallicchio, Implacable Foes, 95; Kirby, War Against Japan, 432.

23 Goldberg, D-Day, 3.

24 Kirby, War Against Japan, 432.

25 Heinrichs and Gallicchio, Implacable Foes, 98. Cf. Goldberg, D-Day, 3.

26 Heinrichs and Gallicchio, Implacable Foes, 98; Rottman, World War II, 378.

27 Heinrichs and Gallicchio, Implacable Foes, 98–99.

28 Morison, History, 233.

29 Heinrichs and Gallicchio, Implacable Foes, 111.

30 Martin, in Saipan: Oral Histories (op. cit.), 157. 

31 Rottman, World War II, 376; Heinrichs and Gallicchio, Implacable Foes, 92.

32 Ibid., 376; Levine, Pacific War, 121.

33 Rottman, World War II, 379.

34 Oral testimony of Sister Antonieta Ada, in Saipan: Oral Histories (op. cit.), 22–23.

35 Oral testimony of Cristino S. Dela Cruz, in Saipan: Oral Histories (op. cit.), 39. 

36 Oral testimony of Manuel Tenorio Sablan, in Saipan: Oral Histories (op. cit.), 37.

37 Vaughan, in Saipan: Oral Histories (op. cit.), 19–20.

38 Oral testimony of Escolastica Tudela Cabrera, in Saipan: Oral Histories (op. cit.), 26.

39 Goldberg, D-Day, 195.

40 VanDusen, in Saipan: Oral Histories (op. cit.), 166.

41 Coox, “Pacific War,” 362; Goldberg, D-Day, 2.

42 Martin, in Saipan: Oral Histories (op. cit.), 158.

43 Ibid., 158.

44 Ibid.

45 Ada, in Saipan: Oral Histories (op. cit.), 23–24.

46 Castro, in Saipan: Oral Histories (op. cit.), 51; in the same volume, cf. Cabrera, 27.

47 Rottman, World War II, 379. Some of these troops were Koreans drafted into the Japanese forces.

48 Ibid.

49 Levine, Pacific War, 124.

50 Rottman, World War II, 379.

51 Levine, Pacific War, 124.

52 Ibid., 121.

53 Coox, “Pacific War,” 363.

54 Kirby, War Against Japan, 452; Allan R. Millett and Peter Maslowski, For the Common Defense: A Military History of the United States of America, revised and expanded edition (New York: Free Press, 1994), 476–77.


Imagery and Combat Art

Image Gallery: The Invasion of Saipan

Combat Art Galleries: Amphibious Operations, Marines in Action 

Saipan Invasion, June 1944

Saipan, 16 June 1944: View of wrecked amphibian tractors (LVT) and other debris on one of the invasion beaches one day after the initial landings (USMC 88365) 

Published: Tue Jun 11 15:24:11 EDT 2019