There were organized guerrilla resistance in Mindanao afterwards, the most prominent one commanded by Wendell W. Fertig, and were largely successful in tying down Japanese units in the island long before the liberation of Philippines began in 1944.

The Allies begun their Mindanao assault in 10 March[2]: 594  and was spectacularly successful afterwards, despite the problems posed by the island itself, such as its inhospitable terrain, irregular coastline, few roads which complicated supply chains, and the thick defense of the Japanese forces.

Believing that the Americans would ultimately attack from Davao Gulf and also anticipating that they would be eventually driven from the city, the Japanese also prepared defensive bunkers inland behind its perimeter where they could retire and regroup, with the intention of prolonging the campaign as much as possible.

With Allied assistance, separate large-sized Philippine guerrilla units were already being formed in eastern and southern Davao Province in anticipation for the upcoming battle.

[2]: 628  The division moved westward across Mindanao so rapidly that the Americans and Filipinos were almost on top of the Japanese around Davao before Gen. Morozumi learned too late that the western landing was, in fact, not diversionary.

By the time the division reached Digos, the Americans quickly overrun the Japanese defenses who were prepared only to repel an assault from the sea westward, not from their rear to the east.

[2]: 624, 628 On 3 May 1945, after months of incessant and intense bombardment by American land-based and carrier-based planes[2]: 628–629  and warships, the first combat elements of the 24th Division entered Davao City against less opposition than had been expected.

[2]: 628  While it took just 15 days, despite severe heat and humidity and constant rain, with an entire division travelling 115 mi (185 km) and seizing the last major Philippine city under Japanese control, the real battle for Mindanao had begun.

[2]: 630 A chronicler for the 24th Division wrote: The soldiers of the 24th Infantry, considered the post-Davao operations to be the hardest, bitterest and, most exhausting battle of the ten island campaigns.

To the foot soldiers fighting in the Davao province, the word abaca was synonymous with hell...Countless acres around Davao are covered with these thick-stemmed plants, fifteen to twenty feet high; the plants grow as closely together as sugar cane, and their long, lush, green leaves are in a welter of green so dense that a strong man must fight with the whole weight of his body for each foot of progress...In the abaca fields, visibility was rarely more than ten feet.

While the infantry sought out the Japanese defenses, platoons and squads worked through the abaca and surrounding jungle to seek out enemy bunkers and spider holes.In this way, fighting progressed slowly, but the Americans and Filipinos were making headway.

At Libby Airdrome and the village of Mintal, some 5 mi (8.0 km) west of Davao City, the 21st Infantry Regiment got assailed from three sides in a concentrated attack by a numerically stronger enemy.

On 17 May, after being exhausted and bloodied during the fighting in Mintal village, the 24th Division, with fresh reinforcements, renewed its offensive, with the 21st and 34th Infantry Regiments attacking against the Japanese center, the 34th east of the Talomo river and the 21st west.

[4][5] As part of the battle the Americans, while engaging in Davao City and its vicinity, were also given the mission to eradicate Japanese troops situated at the western portion of the gulf.

There, they have discovered that the Japanese have mastered the art of camouflage so well that they hid their suicide boats under mangroves with green, freshly cut palm leaves that enable them to be unseen at a distance greater than 100 yards.