Mindanao is the southernmost and second largest major Philippine
island, roughly 300 miles (500 km) across with an area of 36,906 square
miles (95,586 km2). It is mostly mountainous terrain, but there are two marshy river valleys, the Mindanao
River valley on the southwest half of the main body of the island and
the Agusan River valley on the eastern half inland of the Diuata
Mountains. Both rivers are navigable.
Peninsula forms a long, rugged western extension of the
island. Its highest elevation is Mount Matindang at 7956' (2425 meters)
in the center of the peninsula, while Zamboanga at its southwest end is
overlooked by a 4380' (1335 meter) peak. There is a narrow coastal plan
in the vicinity of Zamboanga itself.
Mindanao was not as well developed as Luzon
1941. Its most important port and
city is Davao,
located on Davao Bay on the southeast coast. The Davao area is
dominated by Mount Apo, the highest point on Mindanao at 9691' (2954
meters), to the southwest. Most of the rest of the population lived
along the north and east coasts. The road net was sparse,
but there were two major highways. One began at Digos (south of Davao)
and crossed the southwest plain to Parang on the west coast, continued
there to the base of the Zamboanga Peninsula, then followed the
coast to the northeastern tip of the island. The other started on the
north coast near Cagayan del
and wound inland to join the first
highway halfway between Digos and Parang. Both highways were of poor
quality unsuitable for heavy vehicle traffic. The major products were
hardwood timber and Manila hemp, which was produced mostly by Japanese living in the Davao
area. The indigenous population are the Moro, an Islamic ethnic group
with a warrior heritage who were among the last to continue resisting
Spanish and American rule.
U.S. prewar contingency plans for the recapture of the Philippines from Japan called for the establishment of a fleet anchorage at Dumanquilas Bay on the south coast of the Zamboanga Peninsula.
When war broke out, there was a heavy bomber airfield complex at Del Monte basing 14
Squadrons. The remaining heavy bombers in the
Philippines were to have joined them there, but the move was delayed,
apparently by Brereton so
that the bomber crews could attend a party in Manila on 7 December.
Mindanao was attacked from the opening day of the war, and 56 Brigade Group (Sakaguchi) began landings at Davao on 19 December 1941. The defending troops withdrew after offering only token resistance. Japanese forces made no further moves against the remainder of the island until 29 April, when 124 Regiment (Kawaguchi) landed on the west-central coast and moved up the highways towards Digos and Cagayan del Oro. 32 Base Force occupied Zamboanga on 2 March and 41 Regiment (Kawamura) landed at Cagayan del Oro. Allied forces continued resisting in the interior of the island until 10 May 1942.
Wendell Fertig, a mining engineer who held a reserve commission and was called to the colors before war broke out, took to the hills at the time of the surrender. He subsequently organized a force of several thousand guerrillas.
Operation VICTOR. Victor IV was an Allied operation directed against the Zamboanga Peninsula and Sulu Archipelago to its southwest, while Victor V was directed against the remainder of Mindanao.
Mindanao and the Sulu Archipelago were under command of 35 Army at Cebu in 1945, with the Zamboanga Peninsula protected by 54 Independent Mixed Brigade (Hojo) and 33 Guard Force, about 9000 troops. Jolo was protected by 55 Independent Mixed Brigade (Suzuki) with about 3500 troops (including Navy ground personnel). The remainder of Mindanao was guarded by 30 Division (Morozumi) and what was left of 2 Air Division (Terada) in the west and north, while 100 Division (Harada) and 32 Special Base Force (Doi) guarded the south and east, a total of about 58,000 troops. Morozumi was in overall command and would also take command of 35 Army on 14 July after its commander was killed.
The regular forces assaulting Zamboanga were built around 41 Division (Doe), They would receive significant assistance from Fertig's guerrilla force, which by this time numbered 38,000 organized into the 105, 106, 107, 108, 109, and 110 Divisions and the Maranao Militia Force. There was also a Sulu Area Command with another 1500 guerrillas. Preliminary bombardment began on 8 March 1945 and air support was provided by Marine pilots flying from Dipolog Airfield on the northern part of Zamboanga Peninsula, which had been captured by the guerrillas of 105 Division and further secured by two companies from 21 Regiment flown in on 8 March. Landings began on 10 March three miles west of Zamboanga by elements of 162 Regiment. There was little opposition and Zamboanga and its airfield were secured the next day. The Americans moved north with assistance from guerrillas, encountering their first serious resistance on 12 March. This was overcome by 24 March and the remaining Japanese withdrew up the coast in hopes of evacuation. Flanking landings forced the Japanese into the mountains where they were contained by guerrillas for the rest of the war. Casualties were 6400 Japanese dead and 1100 taken prisoner, another 1385 turning themselves in following the general surrender. the U.S. lost 220 killed and 665 wounded.
Meanwhile, from 16 March 1945 on, small detachments landed in the islands of the Sulu Archipelago, including Sanga Sanga off Tawi Tawi on 2 April and Jolo on 9 April.
VICTOR V was carried out by X Corps (Sibert). 24 Division (Woodruff) led the assault
with the assistance of 3
Special Brigade and was reinforced with 31 Division (Martin). The corps was landed by Amphibian Group 8 (Noble) covered by Cruiser Division 12 (Riggs). The Japanese had
concentrated around Davao, where they expected the main landings, but
24 Division landed at Illana Bay near Malabang
instead, on 17 April 1945. Filipino guerrillas from 108 Division had
already occupied the landing beaches and airstrip, and the Americans landed a single reinforcing battalion
here while landing the remainder of their force at Parang and around
the mouth of Mindanao River. There was no opposition, the pier at
Parang was quickly repaired and used to quickly unload LSTs, and the Americans rapidly advanced
down the highway towards Kabacan
and its road junction. The ground troops received significant support from river craft of 533 Engineer Boat and Shore Regiment
operating on the Mindanao River, which helped drive the Japanese out of
Fort Pikit near Kabacan. 31 Division came ashore on 22 April, the same
day that Marine Air Group 24 arrived at the Malabang airstrip. Davao was
reached by 24 Division on 24 April and the Japanese were driven out of the
city by 31 April after a fierce fight in the hemp plantations west of
the city. The Japanese retreated to a defense line in the hills that
was not broken until 10 June.
On 14 May 1945, a group of PT boats
from Motor Torpedo Boat Division 24 discovered a cove near Piso Point
on the east side of Davao Gulf that sheltered six Japanese motor
torpedo boats. The American boats blazed away with automatic weapons fire, returning the next day with destroyer escort Key to bombard the Japanese base.
Meanwhile 31 Division advanced on Del Monte through difficult terrain, as elements of 41 Division took over rear area security. 108 Regiment landed at Macajalar Bay near Cagayan del Oro on 10 May and advanced to Del Monte, linking up with 31 Division on 23 May. The surviving Japanese fled into the mountains in the northeast, and Filipino guerrillas were again assigned to contain and mop up the Japanese.
Total Japanese casualties in eastern Mindanao were
21,100 killed and 2,696 taken prisoner. Another 52,910 surrendered on 7
September 1945. U.S. casualties were 820 dead and 2880 wounded.
The campaign was controversial, since Fertig's
guerrillas already controlled 95% of the island and had pinned down the
Japanese in the major towns. Even Samuel Eliot Morison, no MacArthur
hater, wrote that "... there seems, in retrospect, to have been no
sound military reason for throwing American troops into this big
island. Even the official Eighth Army Report admits that Mindanao had
no strategic value after Luzon and the Visayas were secured; it even
indicates that this operation was undertaken for reasons of prestige,
and to please our Philippine allies."
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