Battle of Mindanao

• 1. Introduction

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  The Battle of Mindanao was fought on the second largest island in the Philippines, and it presented the Allied forces with their greatest challenge in the campaign to liberate the archipelago from Japanese control. Rain forests. Crocodile-infested rivers. Abaca fields so dense that visibility shrank to ten feet. And a Japanese force that had dug itself so deeply into the terrain that soldiers knew, even before the first shot was fired, that this would be brutal.

  What the American planners understood was that a frontal assault on Davao Gulf would hand the Japanese every advantage they had prepared for. What they chose instead was something unexpected: a landing on an undefended coastline, a drive through over a hundred miles of jungle and mountain, and a strike from the rear. The question was whether the momentum could hold before the monsoon rains came and swallowed the roads whole.

  The story of Mindanao is not a single battle. It is a campaign that unfolded across a geography designed to kill movement, fought by soldiers who learned that in abaca fields, the only way to find the enemy was to wait until the enemy opened fire at a range of three to five yards.

• 2. The Island Against You

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  Mindanao's geography was not merely difficult. A 24th Division chronicler later described the abaca fields as "synonymous with hell," and that description captured what every soldier encountered from the first day. The abaca plant grew fifteen to twenty feet high, as densely packed as sugar cane, and its broad leaves formed a canopy so thick that no breeze reached the men fighting beneath it.

  Beyond the abaca, the island offered rain forests, swamps, and grassland, all of it crossed by rivers teeming with crocodiles. The few roads that existed were fragile lifelines. Highway 1 cut east-west across the southern part of the island, from just south of Parang on Illana Bay to Digos on Davao Gulf, then north to Davao. Sayre Highway ran north-south, starting at Kabacan and climbing through the mountains of Bukidnon toward Macajalar Bay.

  The Japanese had concentrated their strongest defenses around Davao Gulf, which they had heavily mined against an amphibious landing. Artillery and anti-aircraft batteries ringed the coastal shoreline. Believing the Americans would come from the sea, they had also prepared inland bunkers where they planned to retreat and regroup. Their strategy was not to win outright but to prolong the campaign for as long as possible.

  This combination of hostile terrain and deeply prepared defenses meant that any plan relying on straightforward assault would pay an enormous price. The Allied planners understood this. What they built instead was a plan that turned the island's geography into a weapon against the defenders.

• 3. The Illana Bay Gamble

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  On the 10th of March 1945, Lieutenant General Robert L. Eichelberger received formal orders from General Douglas MacArthur to clear Mindanao. MacArthur's staff estimated the campaign would take four months. Eichelberger had misgivings about that timetable, and his Eighth Army staff devised a different approach.

  Instead of assaulting Davao Gulf directly, as the Japanese anticipated, the plan called for landing at Illana Bay on the undefended western coast and then driving more than 100 miles east through jungle and mountains to hit the Japanese from behind. The success of the plan rested on two things: the speed of the initial landings and the ability of the advancing units to maintain momentum before the rainy season made movement impossible.

  X Corps, under Major General Franklin C. Sibert, was assigned the ground operations. Major General Roscoe B. Woodruff's 24th Infantry Division and Major General Clarence A. Martin's 31st Infantry Division were the principal combat units. Rear Admiral Albert G. Noble's Amphibious Task Group 78.2 was responsible for carrying the 24th Division to the assault beaches near Malabang by the 17th of April.

  Then, before the main landings even began, Colonel Wendell Fertig's guerrillas changed the picture entirely. Fertig sent word that his forces already controlled Malabang and its airstrip. Starting on the 5th of April, Marine aviators from Dipolog moved to the Malabang airstrip and, using guerrilla intelligence on Japanese positions, began bombing those targets. By the 11th of April, Japanese forces had fled toward Parang. Sibert, Woodruff, and Noble seized on this development and revised their plans so the 24th Division would come ashore at Parang, much closer to Highway 1, cutting days from the operation before it officially started.

• 4. Zamboanga and the Sulu Islands

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  On the same day Eichelberger's forces received their Mindanao orders, a parallel operation was already underway to the southwest. Remnants of Major General Jens A. Doe's 41st Infantry Division carried out Operation VICTOR IV, the seizure of Zamboanga City at the tip of the Zamboanga Peninsula. Defending that city was a force of about 8,900 men from Lieutenant General Tokichi Hojo's 54th Japanese Independent Mixed Brigade, dug into strong defensive positions.

  The 13th Air Force bombed the landing areas, the U.S. Navy conducted a three-day bombardment, and then the 162nd and 163rd Infantry Regiments came ashore three miles west of the city at San Mateo. Japanese resistance to the landings was minimal, and the city fell quickly. But the day after the landings, on the 11th of March, the Americans ran into fierce resistance in the hills overlooking the coastal plain. For two weeks, American infantry fought along a five-mile front in terrain too rugged for tanks, against positions fortified with earthen emplacements, barbed wire, minefields, and booby traps. Marine aviation and naval gunfire provided essential support.

  On the 23rd of March, the center of the Japanese line broke. The 54th Japanese Independent Mixed Brigade was forced to pull out, harried by guerrilla units as it retreated into the jungle. The final count: 220 Americans killed against 6,400 Japanese dead.

  Alongside Zamboanga, smaller 41st Division units swept through the Sulu Archipelago, rapidly seizing Basilan, Malamaui, Tawi-Tawi, Sanga Sanga, and Bangao. Jolo was different. On the 15th of April, some 3,750 Japanese troops anchored their defense around Mount Daho and held off the 163rd Infantry and Filipino guerrillas in hard fighting before the position fell on the 22nd of April. By mid-June 1945, the 163rd had suffered 35 dead and 125 wounded, while roughly 2,000 Japanese perished.

• 5. The Drive on Davao

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  The 24th Division came ashore at Parang on the 17th of April and moved inland quickly. Eighth Army planners, correctly guessing that the Japanese would destroy bridges along Highway 1, directed the 533rd Engineer Boat and Shore Regiment to exploit the Mindanao River, which ran roughly parallel to the highway and was navigable for 35 miles. Lieutenant Colonel Roberto Amputs commanded a small fleet of gunboats that sailed upriver and seized Kabacan and the junction of Highway 1 and Sayre Highway on the 22nd of April. The nearby Japanese garrisons, startled, fled north and west. The river then became the main supply line, with troops and rations moving far upstream.

  On the same day, the 31st Division came ashore, with Marine Aircraft Group 24 arriving at Malabang to support ground operations. With both divisions ashore and ahead of schedule, General Sibert ordered the 24th to push up Highway 1 toward Digos and then seize Davao City, while the 31st would follow to Kabacan and then drive north up Sayre Highway.

  The Japanese made a critical error in allowing Kabacan to fall so easily. Their 30th and 100th Divisions were hopelessly separated by the American advance, and X Corps built up momentum that led directly to their destruction. General Morozumi learned too late that the western landing was the real assault, not a diversion. When the 24th Division reached Digos on the 27th of April, the defending Japanese were oriented entirely toward the sea and were quickly overwhelmed from behind.

  On the 3rd of May 1945, the first combat elements of the 24th Division entered Davao City against less opposition than expected. The Japanese had spent their remaining time destroying the city before withdrawing inland. The entire division had traveled 115 miles in 15 days through severe heat, humidity, and constant rain, seizing the last major Philippine city still under Japanese control.

• 6. The Abaca Battles

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  Private First Class James Diamond of D Company, 21st Infantry Regiment, was leading a patrol to evacuate casualties near Libby Airdrome on the 14th of May when his unit came under heavy attack. Diamond sprinted to an abandoned machinegun and drew enemy fire to allow his patrol to reach safety. He was caught in a hail of bullets. The posthumous Medal of Honor awarded to Diamond captured something essential about the fighting that followed the capture of Davao City: individual acts of heroism repeatedly spelled the difference between survival and annihilation.

  At Libby Airdrome and the village of Mintal, five miles west of Davao City, the 21st Infantry was attacked on three sides by a numerically stronger enemy. The abaca fields made conventional tactics nearly impossible. Platoons and squads worked through the dense growth seeking out enemy bunkers and spider holes, with visibility rarely exceeding ten feet and no breeze cutting through the heat. More men on both sides fell from heat exhaustion than from bullets.

  By the 17th of May, the battered 24th Division renewed its offensive. The 19th Infantry Regiment, supported by Fertig's guerrillas, broke open the Japanese eastern flank. On the 29th of May, the villages of Tacunan, Ula, Matina Biao, Magtuod, and Mandug fell. The Japanese 100th Division collapsed and retreated, though mopping-up operations against bypassed pockets later claimed the life of the 19th Infantry's commander, Colonel Thomas "Jock" Clifford Jr. The fighting around the fringes of Davao City cost the 24th Division roughly 350 dead and 1,615 wounded, while the Japanese 100th Division suffered about 4,500 casualties.

• 7. Colgan Woods and the Final Resistance

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  The 31st Division pushed north up Sayre Highway while the 24th fought around Davao. The 124th Infantry Regiment, under Colonel Edward M. Cullen, was at the point of the advance when the first monsoon rains began creating havoc. Near Kibawe, Lieutenant Colonel Robert M. Fowler's 2nd Battalion, with Battery B of the 149th Field Artillery attached, ran into a Japanese battalion moving south and engaged it with artillery fire, killing at least 50 and scattering the rest.

  The 31st reached Kibawe on the 3rd of May. Below, a supposed Japanese supply trail twisted south toward the ocean shore village of Talomo in Davao City, and the battle for the Talomo trail on the 11th of May proved as treacherous as any the campaign produced. About 1,000 Japanese held the trail, but torrential rains and impassable terrain were just as dangerous as the defenders. Supplies had to be airdropped. By the 30th of June, the 167th Infantry had managed to advance only five miles beyond the Pulangi River, losing 80 dead and 180 wounded; the Japanese suffered about 400 dead in the same stretch.

  The toughest fight on Sayre Highway came when the 124th Infantry moved through Maramag, 30 miles south of Kibawe. General Morozumi had ordered a Japanese battalion to delay the regiment there to allow his 30th Division to regroup. The battalion did so with such ferocity that it took six days for the 124th to reach Maramag. Banzai charges hit the regiment on the 7th of May and again on the night of the 14th. The second charge was stopped by American automatic weapons; 73 Japanese were killed, ending the battle. In the fighting for Colgan Woods and Maramag from the 6th to the 12th of May, the 124th Infantry lost 60 dead and 120 wounded. The area was later named Colgan Woods in memory of Captain Thomas A. Colgan, an Army chaplain killed while repeatedly going into the line of fire to aid wounded soldiers.

  The 155th Infantry Regiment, under Colonel Walter J. Hanna, occupied Malaybalay on the 21st of May and secured Sayre Highway alongside the 108th Infantry Regiment under Colonel Maurice D. Stratta. Morozumi's 30th Division continued retreating up the Agusan Valley after a final encounter with the pursuing 31st Division on the 5th of June, eventually disappearing into the jungle.

• 8. Surrender and the Final Count

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  General Eichelberger announced the end of organized Japanese resistance, though mopping-up operations by small American units and Filipino guerrillas continued. Pockets of Japanese troops, sheltered in the island's unexplored jungle expanses, survived until the formal end of the war, at which point some 22,250 Japanese troops and 11,900 civilians emerged to surrender. That surrender completed the total liberation of the Philippines.

  Across the entire Mindanao campaign, 12,865 Japanese troops were killed in battle, and another 8,235 were estimated to have died of starvation and disease. The Americans lost 820 men killed and 2,880 wounded for the full campaign, a toll that, given the scale and difficulty of the fighting, Allied commanders attributed partly to the guerrilla network that Colonel Fertig had built across the island.

  Before every landing, Fertig's guerrillas had harassed Japanese units, supplied intelligence about enemy dispositions, and assessed which beaches were suitable for amphibious operations. After each landing, they fought alongside American units and pursued Japanese forces through terrain that American soldiers could barely navigate. The Eighth Army officially described this contribution as a "force multiplier," a phrase that understated how much the guerrillas had compressed the timeline and reduced the casualty count.

  Far to the south, on the 12th of July, the 1st Battalion of the 24th Division's 21st Infantry arrived at the northwest shore of Sarangani Bay to reinforce a reconnaissance patrol that had located a strong Japanese force in the interior. The remaining Japanese retreated into the Klaja Karst in the municipality of Buayan, making their last stand against mixed American and Filipino forces. Operations continued until mid-August, when American aircraft heavily bombed the area. The last Japanese resistance on Mindanao was finally over.