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2. Mines and Similar Items:

a. Numerous enemy mines were encountered set in place, and in magazines or dumps. The following tykes were observed:

(1) Magnetic mines. Found only in dumps.

(2) Shaped charges. Made from Coca-Cola signs. Those were used by the Engineers as bulk explosives to supplement their own stocks.

(3) Lunge type mine. Found only in dumps. This mine appeared to be only two-thids (2/3) the size of those previously reported. No handles were found.

(4) Small Jap Anti-boat mines. This was the only type of mine employed tactically by the enemy. It was encountered in dumps, on the beaches, and on trails. Sae Incl #l.

(5) Molotov Cocktail. It is believed that no previous reports have been submitted on this item. See Inclosure #2.

It consisted of a bottle of approximately eight (8) ounce capacity, similar to those used for carbonated soft drinks. This was filled with a clear viscous liquid, believed to be a solution of rubber and benzene. Around it was a well made rubberized sling, holding a cylindrical glass vial of black crystals. Several of these incendiaries were tested. They worked very well and burned for a considerable tine. A number of cases containing this type were found, but reports indicate that none were employed against our forces. 

(6) Small size type 3 AT-AP mines. Found only in dumps. See Inclosure #1.

(7) Yard stick mines. Only one mine of this type was found, and that on an isolated beach.

(8) Undoubtedly there were other largo quantities of these mines, and perhaps of other types, stored in underground magazines or coves that were covered up or destroyed by our attacking forces.

b.   Employment of Mines:

(1) With the single exception of the one (1) yard stick nine, all of the mines actually laid or employed by the enemy against our troops were of the small size anti-boat type. In all, approximately two hundred fifty (25O) of these mines were located. See Inclosure #16.


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(a) One hundred thirty (130) were discovered on the San Jose beach, laid in the pattern as indicated on Inclosure O. It was here that the Battalion Landing Team of the 34th Infantry landed.

Apparently the Japs had some time previous placed dug in boxes with covers in the beach in the desired pattern. When aware of the imminent assault on the Island, the mines were placed in these boxes. No attempt was made by the enemy to camouflage or to keep this mine field from being disclosed. It is interesting to note that with few exceptions, the whole detonator or "horn" was exposed and in addition there were many instances where part of the base was visible.

This mine field was discovered accidentally by a truck. The Engineers and mine platoon of the Infantry cleared paths through the field, but in spite of these gaps, the mines accounted for: 1-Jeep, 1-2 1/2 ton truck, 1-D-6 and 1-D-7. Several other trucks hit the mines, but merely broke off the detonators without setting off the mine. In view of the fact some unarmed mines were found elsewhere, these malfunctioning ones may not have been armed. It is interesting to note that the D-6 did not hit the nine until D-3. It had been placed out of pattern and had been covered by the debris the dozer was removing. Its effectiveness and power were demonstrated on this D-6. One whole side except for the driving sprocket was blown off and the tractor tipped over on its side.

(b) A mine field on the west side of the North Dock area was found containing some fifteen (15) to twenty (20) mines. These were planted in the same type boxes, but most of the mines were not armed. No pattern was discernable, the distances between mines, however, were generally several yards. Their location was too far from the beach for use as AB mines.

(c) Another mine field was discovered along the beach at the mouth of the James Ravine. In this area the mines were not placed in a definite pattern. The density of the field was about one-half (1/2) mine per yard of front. There was also a single barbed wire entanglement and some anti-vehicle hedge hogs made of steel and concrete in this area.

(d) On the beach between Artillery and Infantry Points were found approximately fifty (50) mines. These were placed in the same type boxes found on the beach at San Jose, but they were in no pattern. Unlike those in the North Dock area, those were all armed.

(e) See Inclosure #4. On the west end of the island a mine field was located on either side of a short steep trail leading from the road to the beach. Of note is the fact that it was impossible to get into the mined area without going through the barbed wire entanglement, hence the value of this field as an obstacle was almost negligible. All of the mine horns were visible and many mines were partially uncovered.

 

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(f) Between Malinta Hill and the Landing Field, an enemy mine field consisting of some fifteen (15) to 20 mines was discovered. The mines were generally staggered along the shoulders of the road. However, there was ample room for a vehicle to pass down the road without hitting the nines.

(g) The fact that this type of AB mine is grate sensitive was brought out clearly by an infantryman. This man, although a member of a mine laying platoon, apparently intentionally kicked the horn of one in place which caused its detonation. 

c. Removal of Mines:

(1) The use of electrical  mine detectors was impracticable on the island due to the large amount of bomb and shell fragments in the area.

(2) With few exceptions, all the mines were readily visible. No attempt was made to camouflage, either by natural or artificial cover.

(3) The enemy mines on San Jose beach, in the north dock area, and those between Artillery and Infantry Points were physically disarmed and removed. The standard methods were used without any difficulties. The other fields were blown in place:

(a.) The 161st Engineers found that a one-half (1/2) pound block of TNT laid against the horn did not work satisfactorily. Evidently the whole horn was blown off and the acid did not flow into the battery cup. A two and a half (2 1/2) pound block of TNT laid on top proved 100% effective.

(b) However, the 113th Engineers had no failures with a half pound (1/2) block laid against the horn.

 

SECTION III - BEACH AND UNDER WATER OBSTACLE:

1. No under grater obstacles were discovered.

2. The only beach obstacles encountered, except mines, were those previously mentioned as being in James Ravine.

 

SECTION IV - FIELD FORTIFICATIONS:

1. General:

The enemy defenses on Corregidor were characterized by the absence of a well conceived and coordinated plan. The island was dotted with well built emplacements, but the vast majority of these were not mutually supporting and hence could be destroyed one at a time.

 

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2. Air and Naval Bombardment:

a. There is and will continue to be much disagreement as to the effectiveness of Air and Naval bombardment. On Corregidor, it was impossible to ascertain just exactly what was destroyed by our forces in 1942, what was destroyed by the enemy in 1942, and what was destroyed in the combined air and naval bombardment preceding the landings. Those opinions and facts were obtained by personal observation and from the Engineers of the task force that recaptured the island.

b. The first impression received of the island was that the installations of the entire fortress were completely neutralized and destroyed, however, upon closer inspection and detailed study of the area, it was amazing to note the number of structures which still remained usable or in some instances, intact.

In the area from San Jose to North Docks, nothing remains but a mass of rubble. Large craters pock mark the area, yet the concrete wall leading to Topside is still intact. Also still undamaged are several lightly built concrete dugouts and magazines, and both the north and south docks are virtually intact.

Malinta Hill received heavy naval and air bombardment yet little damage was done to the mouths of the tunnels, and a searchlight still remains intact on top of the hill.

Inclosuros #5 and #6 are two (2) examples, showing the in-effectiveness of the Naval shelling.

c. It is generally accepted that the Naval bombardment of the west end of the island neutralized many emplacements, not by direct hits, but by landslides caused by the shelling. The air bombardment of Monkey Point is also considered as having been quite affective.

d. The operations carried out on Corregidor seem to confirm again the military axiom that the Infantry has to make the final assault to occupy the ground and to successfully and thoroughly defeat the enemy. The efforts and effects of all other arms are merely to lighten their task.

3. Emplacements:

 a. Types: The great majority of the enemy emplacements were small, hand-dug tunnels or caves facing the road. Sketches of the several different types and the methods of placing the explosive charges to destroy then are shown in Inclosures #7 through #I4. Automatic weapons were used in only five (5%) percent of these caves and tunnels.

 

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 b. Typical locations of emplacements in relation to the terrain and their fields of fire are shown in Inclosure #15. However, this area is developed to a greater extent than is normal.

c. From the above sketches it should be noted that weapons in these tunnels or caves (the names are used interchangeably) covered generally only the area directly in front of the entrance. In numerous instances the guns were emplaced so far back in the tunnels that the field of fire along the road was only a few feet wide. Occasionally the weapons emplaced in one tunnel would cover the approaches to another. It has been reported that several times the Japs set up their guns on the road in front of the caves, thereby obtaining a good field of fire. It is the general opinion that these were the intended tactics.

d. Demolition Tactics: The infantry was interested in closing any caves or tunnels in which the enemy was entrenched, or which were likely to be used by the Japs infiltrating through our lines.

(1) The parachute engineers actually went on patrol with the infantry and proceeded to seal the caves as requested of them. The infantry stated several times that their advance was only as fast as the engineers could close caves and tunnels to their rear. It is believed, however, that the infantry should have given heavier local support to the engineer demolition crews.

(2) The operations of the 113th Engineers were conducted differently. Their demolition crews did not go with the infantry patrols, but were contacted by the infantry when there was a demolition job on a cave or tunnel. Then, with excellent close-in support by the infantry, carried out their mission of destroying enemy positions and fortifications.

(3) The location of these caves was such that only direct fire weapons could be employed successfully. In most cases the terrain and condition of the roads limited these to hand carried weapons. The bazooka with WP rockets was by far the outstanding weapon. The WP grenade was also very effective. Fragmentation grenades were found to have little effect in the caves. Flame throwers were not very effective and were seldom used. An equivalent weight of about seventy (7O) pounds of TNT was found to be more practicable from a weight, transportation and effectiveness standpoint.

(a) Artillery fire was not used extensively against the caves. The great majority of pieces were 75mm howitzers, whose light shell had little demolition effect. Mortars too were ineffective against emplacements.

1. The demolition tactics generally followed this pattern:

a. Since the emplacements or caves were not usually mutually supporting it was possible to approach them one at a time.


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With riflemen or BARís covering the entrance, a bazooka or grenades were fired into the cave. This had one of two effects. It drove the enemy into the rear of the cave and neutralized their fire or it drove them out in the open, where they wore shot down. Then the Engineers or the Infantry demolition parties placed the charges as shown in Inclosures #8 and #9. Many times these demolition parties could actually hear the Japs chattering inside while they wore placing these charges. Surprisingly few casualties were suffered by this method of operation. Occasionally tanks were used with this team to furnish point blank fire into the tunnel.

b. When the 113th Engineers landed, their dozers were used very successfully in cave covering and tunnel blocking tactics. This equipment was used to completely seal caves or tunnels only partially closed by explosives or to cover the entrances to new ones. One method used was the dozer-tank team. The tank fired point blank into the cave, while the dozer picked up a large load with its blade. The tank stopped firing while the dozer pushed its load in front of the entrance. This routine was repeated until the mouth of the cave was closed. Special mention should be made here of the courage and valor of the dozer operators, since those operations were carried out without benefit of an armored cab. The dozer - infantry team was also successfully employed using similar tactics.

c. There were as many methods of blowing those caves as there were demolition crews. As a general rule, two (2) charges of fifty (50) pounds to one hundred fifty (150) pounds were placed inside about six (6) to ten (10) feet from the mouth. It was found that larger charges blow the spoil completely out of the entrance. Because of the steepness of the slope and the great depth of over burden, very few were blown by externally placed charges.

SECTION V - SUMMARY.

1. Much of the success of this operation is due to the splendid work of the three (3) engineer units participating. The tactics were such that the infantry could not hold ground unless they were protected from the rear. The best protection was provided by the systematic destruction of the caves and tunnels used by the Japs as shelters and hideouts.

2.   The engineers, and to a much lesser extent the infantry, closed those caves with explosives or dozers. The engineers alone neutralized over three hundred (300).

 

EARL McFARLAND, Jr,
Major, C. E.
Asst Engineer

 

 

16 Incls:

Incl #1 Sketch of AB mine and non-metallic mine.

Incl #2 Sketch of Molotov cocktail.

Incl #3 Sketch of mine field, SAN JOSE BEACH.

Incl #4 Sketch of mine field and barbed wire, W end of island. Incl #5 & 6 Effect of naval shell fire

Incl #7 to #14 inclusive Sketches of typical caves and tunnels.

Incl #8 Methods of destroying Jap Caves on Corregidor Island

Incl #9 One Method of Destroying Japanese Beach Caves on Corregidor

Incl #14 Tunnels for Servicing Coast Battery
Incl #15 Schematic Diagram Showing Typical Defensive Area
Incl #16 Typical defensive area.

 

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transcribed by EXO 040408

 

   

 

 

 

 

         

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