641 Tank Destroyer 2nd Battalion Platoon: Blasting East Caves, Mokmer Ridges

by Dr. Hargis Westerfield, Division Historian with Captains H. Richard Gerttula and Bennett Saunders


On 2 June 1944, 2nd Platoon 641 Tank Destroyer Battalion began our second Battle of Biak. We received six new 4.2 mortars to replace the six which we had lost in rear-guard action to extricate 162 Infantry from Parai Defile. (We had to destruct our first six mortars because 162 ordered us to leave them.) We spent all 2 June readying our new six mortars for action.

The very next day, we fought again. To cover K 162's right flank and C Battery 205 Field Artillery which took harassing fire from Parai Cliffs, Lieutenant Sandwick had us occupy positions 300 yards west of Ibdi. Beginning 1930, we shot eight rounds white phosphorus (WP) and 14 rounds high explosive (HE). When the close fire made "K" nervous, we ceased at 1330. (For these HE shells - M-3 - contained 25 pounds TNT.)

And starting 7 June, 2nd Platoon fought almost daily, nearly six weeks through 14 July. We fought Parai Defile again. Embarking on our 4 DUKWs with our fine Black Quartermaster drivers, we followed 162's I, K, Cannon Companies and six tanks to Parai Jetty. By 1900, we began registering to protect 162 and tanks - with four WP shells, then six HE. Our position was 600 yards east of our great rear-guard location of 29 May when we protected 162's retreat but lost our first mortars.

Next day, 8 June, we supported 162's push west to Mokmer Village to try to contact 186 at Mokmer Dromes. Our observation party got badly mauled. This was after the morning when 162 advanced into the coconut plantation where the Japs had struck with tanks on 29 May. At first, 162 found no Jap opposition.

But at 1330, heavy mortar fire from East Caves halted 162. At 1340, D's 2nd Lieutenant Joseph P. Russell phoned to request that we adjust fire to spring 162's men from their prone positions under fire. We fired one WP, three HE shells. Then at 1400, Jap shells cut the wire. We never heard Russell's voice again.

Lineman Kelly rushed back with the sad news Russell was dead, Pedergast and Daly wounded. Gerttula organized a new observer party under Staff Sergeant Roy White (White was that kind of NCO always on the spot when "D" needed him.)

Kelly guided the new observation post back into the forward area, and by 1700, we fought again - interdictory fire - nine WP, 60 HE.

Temporarily, White silenced those mortars high in the dark- green coral terraces. He got a direct hit on a Nip machine gun. (White's fine work here and elsewhere would earn him a battlefield commission as 2nd Lieutenant.)

Next day, 9 June, Jap fire from East Caves increased steadily while 162's 1st Battalion and 3rd Battalion pushed doggedly west. At 1400, "D" adjusted fire at 50 yards greater range against East Caves. With two WP, 22 HE, we momentarily silenced the Jap mortars. At 1730, we shot 16 HE on that safne ridge area, but at 1900, the Japs hit 162's Headquarters. Despite 70 more HE shells, Jap mortars continued fire. (And tanks in LCTs offshore had pounded East Caves all day, but without success.)

On 10 June, Jap mortar fire was again heavy. Their shells hit 162's supply road to the-new forward positions at Mokmer Dromes. To safeguard passage of seven tanks with 15 supply trucks, "D" started battle at 0800. Rate of fire was at a minimum of one round per minute, 0800 to 1515. Meanwhile, tanks fired on East Caves from LCTs offshore; and 205 Field Artillery and 947 Field Artillery arced in projectiles.

But most effective shelling was surely from 641 TQ. For when we paused at 1000 to shift base plates, six Jap mortar rounds hit Mokmer Road and killed one man, wounded five. Soon fighting again, "D" apparently killed the Jap mortars. On 10 June all day through 1515, we had fired 890 rounds or 18 tons. Apparently the Jap mortars were destroyed.

But on 11 June at orders from 1st Battalion 162's Major Benson, we fired the same concentrations - beginning 0645. Jap shells were still hitting Mokmer Road. After 145 rounds HE, we quit firing at 0858. From 0858 to 1930, our troops and vehicles travelled the road freely. When the Nips opened up again at 1930, we blasted them silent with 60 rounds HE in 15 minutes.

On 12 June, these diehard Nips smashed Mokmer Road once again. Beginning 0700, we hit them this time with a third of our shells white phosphorus - 38 WP and 77 HE, precisely. The WP was devilishly effective; observers reported that Japs leaped from their holes and screamed with pain. Again, "D" had reopened the road for supplying 162 which now fought to capture the ridge guarding West Caves.

But we still lacked adequate observation of Jap cliff-top installations. Observation planes were unavailable. So on 13 June, G-3 sent Gerttula out on an LCT with three tanks to shoot from the sea and help reregister our 4.2s. At 1740, we crashed the ridge with 15 WP and 290 HE. Again we freed the road for Yank vehicles.

On 14 June, "D" got Gen Doe's orders to move into the fight to close the Great Gap between 162's 2nd Battalion and 3rd Battalion on Mokmer Ridge before West Caves. Despite 162's dogged advances under heavy field artillery shelling, the Great Gap was still 500 yards wide. From this gap, Jap warriors denied the use of Mokmer Dromes to our bombers. And on 15 June at 1645, we registered on four Jap naval guns in the Great Gap - with 38 HE shells.

Our fire was surely decisive in helping 2nd Battalion 186 close that Great Gap. For while 186 waited orders to move out on 16 June, our 4.2's fought for 186 with all that we had. Working with the infantry mortars, we poured in steel on the Japs.

We searched and traversed a Great Gap area of 200x500 yards. From 0800 to 0850, we expended 379 HE. Although 162 had been stopped the day before, 186's "shock troops" of 2nd Battalion had comparatively minor resistance to close the Great Gap - except for E 186's 2nd Platoon. An estimated 40-50 dead were found in our impact area.

Next day, 17 June, "D" harassed the "main road to West Caves." Covering 300 yards of road, we shot nine WP, 115 HE. Because of a defective tube, No.3 mortar shot erratically. We quit using it until we replaced the tube on 21 June. At 1310, the 81s, field artillery, and we fought a Jap fieldpiece. After 1 WP, 110 HE from us, it ceased fire. Thus during 15-17 June, we were in battery to help 186 and 162 seal off West Caves for the final kill. After five days' in action, 2nd Platoon D 641 fired again on East Caves.

Except for sporadic fire at trucks on the coast road, East Caves was inactive. But by 23 June, Jap mortar and small arms fire picked at engineer work parties on piers and roads. We registered on East Caves from the ground; then Lieutenant Colonel Cochran adjusted us more precisely from the air. Even then, of 315 rounds WP and HE, only some 1/4 of them hit that narrow target of ridge-side caves. Our fire did silence them, but on 24 June, we had to drop 49 WP and 120 HE to quiet them again. On that same 24 June, we broke down mortars to entruck again. While 162 mopped up West Caves, 186 needed D's 4.2s on Jap positions northwest of West Caves - some 600 yards northeast of Borokoe Dromes.

By 1830 that 24 June, D's 2nd Platoon registered - probably on the strongpoint where some Jap 75 harassed 186. Since D's observers with 162 had not returned, Commanding Officer Gerttula himself and Kelly climbed the steep ridge to attempt observation in an opaque terrain of tall jungle and defiles.

With direct observation impossible, they started registration at long range, then shortened range by sound-sensing with eight rounds WP. Then they computed a normal barrage of sweeping fire on an area 400x400 yards. This barrage impacted about 1900, with an unrecorded number of shells. To penetrate the dense cover, they employed delayed fuze. When 186 took the ground, they found that D's fire was accurate indeed. Even our registration rounds had landed accurately on target. Jap positions and weapons were recently deserted. Gerttula believes that this was the shootout after which several dazed prisoners asked whether we fired "automatic artillery."

On 27 June, we fought another Nip strongpoint for 186's 3rd Battalion. In opaque terrain again, we accurately placed 120 WP, 83 HE. When "L" hit the area, they found 32 Jap dead. Our observer was James White, newly made Lieutenant that 27 June 1944.

But Japs still held East Caves, and shot up Mokmer Road. Gen Doe recalled Gerttula for consultation with G-3 to kill those caves. On 28 June, we displaced a 4.2 to where it could mark the Caves for an air-strike. Gerttula adjusted fires with an Air Force OC3 and 12 WP shells. Then 405 Bomb Squadron struck, but the Caves still harassed E Company 542 Engineer Boat & Shore Regiment working in a gravel pit northwest of Mokmer Village.

Now 2nd Platoon had our last Biak mission. On 29 June, we had our old position 300 yards east of Mokmer Dromes. On this exact date in May, we had shelled those caves in desperate rear-guard action to save 162 from annihilation.

Orders were to fire on East Caves until further notice – 15 rounds hourly, at irregular intervals. From a Division Artillery plane, our newly commissioned Lieutenant White adjusted fire. We set up a firing schedule to give each mortar a one hour turn to impact its irregularly timed 15 shells and keep 2nd Platoon in action 24 hours a day.

Division G-3 organized the reduction of East Caves like the siege of a great city. Besides 641 TD’s 6-mortar pounding, a gun of C Battery 205 Field Artillery smashed 800 rounds of smoke and HE into the caves. North of them, I-163 guarded possible Nips’ escape routes or counter-attacks while E 542 Engineers patrolled or hit some caves with bazookas.

Near daylight 0430 30 June, our crews saw a great fire in the cave mouth area. It burned 30 minutes. From his plane at 0800, White decided that we had flamed two Jap bunkers. Probably the WP shells had caused these flames.

We continued blasting East Caves every day at 0800 and 1800, from 30 June through morning of 3 July. Gerttula and White flew about to keep our mortars precisely adjusted. Some two-thirds of our rounds landed in the large cave.

At 1025 3 July, orders came to cease fire. During a 4-day span, we had fired 348 rounds WP, 873 HE, all of 1221 rounds. The 348 WP rounds had been mainly for night action, at which time we found aiming lights were necessary.

In those 4 days, not one Jap round had hit road or docks. Actually, the Japs' last heavy rounds fell about 2000 3 July, but General Doe knew better than to let up firing until days later. For that sheer cliff wall of Parai Defile was a network of caves and sumps, with anti-aircraft guns, heavy mortars, heavy machine guns, as 162's 2nd Battalion and 3rd Battalion well remember. Although the Japs, for reasons unknown, had failed to make maximum use of East Caves after 10 June, over three weeks ago, this was readily the strongest position on Biak.

But after 641 TD ended the menace of Jap heavy weapons, light harassing fire continued. On 3 July, our last firing day, E 542 EB & SR and E 163 penetrated some caves. On 5 July, they dared invade the larger sump holes. In one cave alone, were four 20 mm guns, 500 rounds Jap 81 mortar shells. In another were two 20 mm guns, a .50 caliber heavy machine gun and a .30 light machine gun. Yet Japs lurked there still killed six Aussie Air Force souvenir hunters 15 July. On 17 July, tanks and infantry killed two machine gun nests. Final resistance ended only on 20 July.

D Company, however, was long gone from Biak by 20 July. For S-3 of entire 641 TD Battalion, Captain Saunders, came from

Hollandia to liberate us. Saunders wanted to prevent demoralization by post-action labor assignments. Even if all "D" had lost just one killed in action, five wounded in action, we were close to breakdown. After two New Guinea years, almost everyone had malaria, dysentery - Saunders himself with tropical ulcers up to his armpits.

            General Doe wanted us an organic element of the 41st, but 6th Army Headquarters had us attached, and Krueger ordered us back to rest-camp at Tahnamerah Bay near Hollandia.

Waiting to embark at Bosnek 14 July, "D" celebrated. Unhappy at returning to their QM outfit, our 12 fine black DUKW drivers scoured Biak for a farewell feast - including canned turkey and fresh fruit. General Doe and all of his available staff attended, and Doe presented us a letter of commendation.

D Company 641 TD's 2nd Platoon waged a great Battle of Biak. After losing our first mortars to save 162 on 29 June, we got new mortars and battled East Caves again. We kept Mokmer Road to West Caves, enabled 186 to close the Great Gap on Mokmer Ridge. And our final five days' battered made East Caves an almost harmless shambles. D's 2nd Platoon played a great part in winning Biak for the 41st Division.


CREDIT:  Credit is due to Gerttula's letters in 1974; but Saunders' 1974 letters started correspondence, supplied invaluable background, found Gerttula for me. But Gerttula alerted me to procure 2nd Platoon 641 TD's Journal which Federal Arcnlves' employees overlooked. Other records are "Operations Journal 98th Chemical Battalion (Motorized) 12 April-31 July 1944," RR Smith's Approach to the Philippines. (Late in Biak action, 641 TD was renamed 98 Chemical Battalion.)