Battle of Ipo Dam

Battle of Ipo Dam / Norzagaray, Bulacan

The Shimbu group situated in the mountains and hills east of Manila controlled extremely important installations of the Metropolitan water supply system. Under Gen Shizuo Yokohama, the 50,000 strong Shimbu group fought with the Allies all throughout the early months of 1945.

Due to the drastic water shortage and deteriorating sanitary conditions in Metro Manila, Gen. MacArhur ordered Gen. Walter Krueger via radio on 10 April 1945 to seize Ipo Dam from the hands of the Japanese. Gen. Krueger tasked the US 43rd Division headed by General Wing to launch the operation. Attached with the 43rd Division are guerrilla forces mostly from the Markings Fil-American Regiment, one of the biggest Filipino guerrilla units during the war, under Col Marcus V. Augustin. The Allied Forces attacked on the night of 6th May which completely surprised the outer defenses of the Japanese. The 169th, 172nd and 103rd Divisions attacked from the South as elements of the 169th Infantry and the Markings regiment attacked from the western sector. The 1st “Yay” Regiment and the 1st Battalion of the 2nd “Yay” Regiment of the Marking’s guerilla unit gathered in Angat, Bulacan. The Markings combated in a small engagement against the Japanese Mapuya Signal Corps in the Hill 21 and killed around nine Japanese soldiers.

The first fierce fight erupted on Hill 535 where elements of the Markings and Kasama Battalion clashed to capture the strategic area. By 12th May, Markings in the northern sector broke through the strongly defended Japanese positions after the heavy air and artillery bombardment. Throughout the battle, hundreds of fighter bombers from the Fifth Air Force dropped gallons of napalm to destroy enemy defensive positions and demoralized the Japanese troops. Ipo Dam was captured on 17 May when the Markings permanently captured the facilities intact.


Smith, Robert Ross. “Triumph in the Philippines: The War in the Pacific.” University Press of the Pacific, 2005.

Salazar, Generoso P. et al. “World War II in the Philippines: Manila Bicolandia and the Tagalog Provinces.” VFP: Manila, 1995.

“Alab ng Puso: The Filipinos in World War II.” DND-PVAO.

PVAO Digitized Collection


May 17 2023


All Day

Local Time

  • Timezone: America/New_York
  • Date: May 16 - 17 2023
  • Time: All Day



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