U.S. Navy (7th Amphibious Force, Zamboanga Attack Group): The Perfect Amphibious Landing

By Dr. Hargis Westerfield, Division Historian

 

            The beachhead landing of the Zamboanga Attack Group for our 41st Division on 8-12 March 1945 is rightly called "the perfect amphibious landing." By "perfect," we mean beaching our 41st in minimum time with minimum casualties. Army-Navy planning was excellent, and Air Force errors luckily failed to cause large losses. The Japanese did help us; they had the wrong defense orders!

            Reasons for Zamboanga. But why did our forces hit Zamboanga? We needed a base to cut the Japs' main supply line for oil from Borneo, which line was south of Mindanao Island. We needed a base for starting arms and ammo for the southern Filipino guerillas. We needed to start freeing Mindanao from the danger of Nipponese atrocities.

            Our Task Force. To make this perfect landing, Vice Admiral D.E. Barbey had a complex Task Force. Light cruisers Boise and Phoenix were his heavy bombardment group. For protection against small suicide boats' torpedoes, he has 21 PT boats. He had 11 minesweepers for inshore protection.

            For beaching men, tanks, field artillery, and supplies, Admiral Royal had a varied amphibious unit, including 543rd Engineer Boat & Shore Regiment. Besides many tracked landing craft (LVTs), there were 32 infantry landing craft (LCIs), and 23 capacious tank landing ships (LSTs), we had a giant dock-carrying landing ship (LSD), and 4 high speed transports (APDs).

            For close protection of these Amphibs., we had 16 more LCIs, some with rocket launchers or mortars. Ten more destroyers would screen this amphibious flotilla by day or night.

Two floating rehearsals were needed to make the assault waves to land on the right beaches at the exact time.

            Softening Up. At sunrise 8 March 1945, two days before we landed, Admiral Berkey's cruiser-destroyer bombardment group stood offshore at Zamboanga to blast important targets. Minesweeping and hydrographic recon began, while some Jap small arms and .75 mm guns were silenced. At 0845, our small Marchine combat air patrol downed a Jap plane. At 1320, Jap demolition charges blew up the land end of Zambo City Pier.

            On 9 March came more mines weeping and hydrography. Jap mortars and light field artillery fired on minesweepers but damaged none. PT boats (heavily armed torpedo boats) arrived and began to prowl for Jap small craft around great Basilan Island. By dark, bombardment and inshore groups retreated into open sea for safety.

            Importance of Hydrography. Accurate hydrographic measurement of beachside currents and depths was crucial. (For on Biak in 1944, the unexpected strength of offshore currents had scrambled our landings and could have caused disaster from alert Japanese.)

            By the time of Zamboanga, however, hydrographers could inform us to deflect our assault waves 20 degrees westward of the expected landings. We had to bypass the long shoals of Santa Cruz Island south of Zambo City. Then, even after we had set up the Line of Departure for landing craft, we had to allow for a strong current through a deep channel. Finally, another strong current 900 yards off the beach would cause LVT drivers to change course again.

            Actual landing area was limited to two narrow beaches each 350 yards long west of Gavilan Point and before the Airstrip. But even inside those 700 yards, shoals and coral heads would endanger the fast runs of our assault craft to the shore.

            For two days before D-Day, we carefully scouted those beaches with air photos and Amphibious Scouts of the Army's 543 Engineers. Except for one long shoal near the foreshore, Yellow Beach had 250 yards of open water all the way in for the first waves of tracked landing craft and Infantry LCTs. For this great fleet of small craft, Red Beach 2 had 100 yards clearance. We found 14 slots for the great LSTs carrying tanks and field artillery and tons of supplies.

            D-Day, 10 March 1945. At 0636 10 March 1945 came our order, "Commence the Approach." Combat Air Patrol planes were already the air. At 0645, naval fire concentrated on the general beach area - about 6,000 yards long by 1,500 yards wide. By 0745, the Control Unit - three subchasers and an LCI - had marked our Line of Departure, 37000 yards from the shore. Landing Tank Ships (LSTs) were ready to unload their craft in order of embarkation.

            YMS ships were already sweeping for mines within that 37000 yards. Receiving Jap fire, they fought back with their 40 mm and 3-inch guns. But they found just one mine.

            Already the APDs - high speed transports - and LSD Rushmore, had been unloading tracked landing vehicles (Rushmore carried a whole dock of water inside herself.) Four great LSTs - tank landing ships - also emptied themselves of LVTs. By 0847, five waves of daring LVTs were driving hard for the beaches.

            And our planes had struck already. Two flights of 12 Liberators each bombed near the Airstrip. Three other Liberator flights totaling 15 bombed near the landing beaches.

            Then four waves of Infantry landing craft - LCIs - about 30 of them, embarked to reinforce the LVTs. At 0923, "mild machine gun fire" came from the beaches, but soon halted. At 0944, Jap field artillery and mortars hit our LCIs - scattered and poorly timed. LCI 710 took 28 little punctures, had three slightly wounded. LCI 779 had four wounded, just one seriously wounded. All landed safely.

            Ninth wave consisted of LSMs - "landing ships medium," all carrying 300 tons of supplies. LSTs had towed them from Mindoro. Four LCIs guarded their landing. Next would be the turn of the heavily laden LSTs to land.

            But what ordeal did the first waves have to endure when they actually hit the beach.  No Japs fought that infantry, but just past the western foreshore, they were blocked by an 8-foot bank of loose and large-sized rubble. LVTs could not climb this wall; they rolled back under their treads. With their heavy equipment, infantry had trouble to climb this rolling 8-foot wall. The assault LVTs moved to the flanks and secured the beach for later waves to land. Wave No.9 of 10 LSMs had special trouble to climb that slope with a cargo of vehicles. Bulldozers landed to breach this bank.

            At 1040, Jap gunfire increased. But it was short or over that bank which sheltered debarking men. After 15 minutes' silence, the range lifted and splashed shells into the sea. But it was almost impossible to hit craft in the water 

            That afternoon, the LSTs took much fire. LST 591 was holed through the ward-room. Left of it on the beach, LST 626 took three shells, one on port bow at water level, a second ricochet that finally exploded in a 20 mm box. Third shell slashed many holes in a forward tank. Until 1800 hours, there was sporadic Jap fire.

            It became a perfect D-Day landing, that 10 March 1945 for our 41st Division. Within the first hour, 6,200 Infantry with 716 Tank Battalion's A Company were ashore. By midnight, 14,000 tons of supplies and vehicles had landed - about 75 percent of the whole cargo.

            Near-Disaster From Our Own Planes. Three uncontrolled lights of planes from near New Guinea almost caused deaths of our own infantry already landed. At 0845, 24 Liberators with 120 I,000-lb. bombs impacted around San Roque Village. But no 162 Infantry had yet got that far. At 0934, 18 more Liberators with 90 more heavy bombs hit Jap defenses at the Airstrip. They just missed our advancing Infantry.

            After that second threatening flight, General Doe on Flagship Rocky Mount asked Brigadier White, Deputy Air Force Commanding Officer, to halt other flights. White blanched and told Doe that he lacked radio contact with those planes. Third flight of 24 Liberators with 120 1,000-lb bombs hit near Santa Marchia Village, but impacted long before 2nd Battalion 163 Infantry had arrived.

            (During the landings, however, there were many other successful sorties. General Doe especially credited the planes for pulverizing Caldera Point emplacements, which could have enfiladed White and Red Beaches.)

            Ground Defenses. When 162 Infantry probed for San Roque strong points and 163 Infantry scouted towards Zambo City, they were amazed at the strong beachside fortifications. They were also surprised that these entrenchments were un-manned. Most of them extended all the way from Baliwasan River east into Zambo City.

            They were based in concrete and amply camouflaged. Many great pillboxes were built of reinforced concrete 2-3 feet thick. Palmetto logs and loose gravel were piled around their bases. Usually one gun-port could enfilade the beach. If there were two, one faced the sea. Heaviest fire would come from vicious 20 mm machine-cannon, many from wrecked planes.

         Near Zambo City were wire tangles which attacks could avoid only by charging into machine gun fire lanes. Camouflage made them impossible to see from air photos. Only the guerillas could tell us of their locations. Tropical grass from the heavy rains had overgrown and hidden them.

            Zambo City forts were built even more formidable to cover main streets and the plaza. One fort consisted of four machine gun nests 50-60 yards apart with a pillbox on each of the line, and connected by shallow trenches. The nests were made of logs and sod, but the pillboxes were lined with 3/4 inch armor plate, and covered with logs and sod. Bases were 6-8 feet thick, with three firing ports. Rear entrances had blast walls for protection.

            But the beach mines were defective. They were contact land mines like depth charges 36 inches long by 18 inches in diameter, placed 100-300 feet apart. At times they were paired across the road. Yet detonators were poor or inserted unskillfully. Many would never have exploded.

            Greatest weakness was that we found the positions unoccupied. Latest Jap command doctrine was that the positions would be vacated until after our bombardment, and then reoccupied.

            But guerillas said that General Hojo had made a kind of compromise with this doctrine. Japs had held the positions from mid-afternoon to 0600 at dawn, then had gone back into the hills. Thirty-six minutes before our Navy bombarded, the Japs had left for the hills! If they had lingered in their lines just 36 minutes, much American blood might have been shed to overrun them.

            Afternoon of Day-Day and D+1 (10-11 March 1945). By 1332 10 March, all 22 LSMs had unloaded their 22 300-ton cargoes. Even earlier than the last LCMs unloaded, the first LSTs had landed Nos. 579 and 626. By late afternoon, 17 of the 22 LSTs were unloading their 600-ton cargoes.

            Happiest men of the whole Attack Force was surely 600 41st Infantry veterans. Although scheduled for rotation stateside, they were assigned as 50-man crews for each of the 12 LSTs carrying most of the Division. After the LSTs retracted, they would return to their staging area on the first available shipping.

            During the night, seven LSTs had unloaded and retracted. Nine were still unloading, and five more still had to land. It was a fine time for Japanese attacks.

            At 0915, Jap mortars fired to the left of Yellow Beach 1. A destroyer and close-in LCI rockets craft barraged the area. About 1030, Jap shellfire flamed an oil-dump near the airfield inside the 41st's lines. About 25-50 percent of it was burned. Many casualties occurred in the Army Shore Party. Cruiser Boise fired a few accurate salvos, and enemy fire gradually died out.

            But on this second beachhead day, our Navy operation was almost wound down. Only two LSTs were left to finish unloading on the third day because of unusually difficult cargo. By late afternoon two convoys were ready to depart for their bases, on Mindoro or Leyte. The perfect amphibious landing was accomplished.

            Casualties. As we can now expect, casualties were light. Only one man was killed while ashore from LST 591. On LCI 779, one was seriously wounded, two slightly wounded. On LCI 710, three were slightly wounded. On the second afternoon, the Group Surgeon, Commander Brunner, was wounded in the leg. There were also reported 10 killed, and 14 others wounded. But we have no other details of those few casualties.

            Final Comments. We salute Vice Admiral D.E. Barbey and Rear Admiral Forrest Royal for their perfect landing of our 41st Division. Their Zamboanga Attack Force based the landing on a careful coastal survey. Discerning hydrography of Barbey's 7th Amphibious Force prevented a scrambled landing like that of Biak. The Japs lacked the planes and Navy for successful opposition. They erred in trying to hit water-borne moving vessels with light field artillery - and moreover, in failing to man their formidable onshore emplacements. Our three misguided Air Force flights did us no harm. Admirals Barrey's and Royal 's was a splendid beachhead.

 

CREDIT: Most important contribution to this history is the 67-page Report of Amphibious Attack on Zamboanga, Mindanao, by Commander Amphibious Group Six (Vice Admiral D.E. Barbey.) It amounts to maybe 16 Sub-topics that are sometimes not quite in harmony. Particularly interesting are 14 pages of play- by-play chronology. This document I found in Marine Headquarters in Washington, on my 1989 Grant. Vol XIII of Samuel Eliot Morison's History of US Naval Operations in World War II  contains a brief section with some worthy insights. General Doe himself told me of Air Force General White's stress when those three plane flights went wrong.