[Lone Sentry: Enemy Mines on Leyte]
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"Enemy Mines on Leyte" from Intelligence Bulletin, February 1945

[Intelligence Bulletin Cover: February 1945]  
The following report on Japanese mines on Leyte originally appeared in the February 1945 issue of the Intelligence Bulletin.

[DISCLAIMER: The following text is taken from the U.S. War Department Intelligence Bulletin publication. As with all wartime intelligence information, data may be incomplete or inaccurate. No attempt has been made to update or correct the text. Any views or opinions expressed do not necessarily represent those of the website.]


First reports from Leyte tell of increased use of land mines by the Japanese defenders.

As had been anticipated from the trend of previous operations, U.S. troops landing on Leyte found that the Japanese had made practical and extensive use of minefields and booby traps in the planned defense of the island.

Preliminary reports indicate that although a decided effort at mining had been attempted, improvised mines were used more often than standard enemy demolitions. Chief of these were aircraft bombs set into the ground with an armed nose fuze exposed as the detonator. A haphazard use of bombs in this manner was encountered before by Sixth Army troops in several Southwest pacific operations.


On Leyte, the principal minefields were found on the air strips at Tacloban and Dulag. Here 63-kilogram aircraft bombs had been planted in groups of three at intervals along the length of the runways—an obvious attempt to destroy aircraft which might try to land on the strip. Bomb mines of this type were planted also on the beach which runs parallel to the nearby Tacloban airfield and which was a logical vehicle route. Near Dulag, armed bombs, which could be detonated by a truck tire brushing against the fuze, were laid on the surface along roads and camouflaged with grass.

[Tacloban air strip. Dots indicate the approximate location of Japanese bomb mines found buried on the runways and the nearby beach.]
Tacloban air strip. Dots indicate the approximate location of Japanese bomb mines found buried on the runways and the nearby beach.

In addition to the bomb mines, the Japanese on Leyte employed two types of improvised mine that have not been found in general use in past operations. These were the so-called "coconut mine," and an improvised box mine.


The coconut mine was a simple but not particularly effective device. The Japanese had taken a large quantity of coconut shells, hollowed them out, and then filled them with black powder. A Model 91 hand grenade was imbedded in the powder, with only the grenade's 5-second pressure detonator exposed. These makeshift antipersonnel mines were used as pressure detonated booby traps, and were easy to camouflage in natural surroundings. An observer has reported that these improvised demolitions also served the enemy as hand bombs when whirled and thrown at the end of a 3-foot fiber rope. On detonating, they made a terrific explosion, but did little damage.

[Japanese Coconut Mine]
Japanese Coconut Mine


Crude, improvised box mines were found to be a fairly common device. Constructed in several sizes, these mines consisted of a wooden box filled with picric acid or ammonium picrate explosive blocks. Like the coconut mine, these demolitions were detonated by a Model 91 or Model 97 pressure-detonated hand grenade which was set into the explosive, but with the armed fuze exposed. Many of these mines were found hidden in the grass along roadsides, or set as booby traps beneath staircases and floorboards in houses where the Japanese had been storing ammunition.

[Japanese Improvised Box Mine]
Japanese Improvised Box Mine

Many different sizes of this box-type mine were found constructed for time-fuze or electrical detonation. On the Maintez River the retreating enemy attempted to demolish a bridge with eight of these mines bolstered by 21 cases of 75-mm shells. The electric caps used were of a type similar to U.S. manufacture.

Although improvised mines were most common, many standard Model 93 (tape-measure), Model 99 (magnetic), and Model 3 (pottery) mines were found stored in ammunition dumps or emplaced along roads as antivehicle demolitions. Some Model J-13 antiboat mines also were found on A-day near the landing beaches ("A-day" for the Leyte operation was the equivalent of the familiar designation, "D-day").


At one place a tank trap consisting of a ditch 20 feet wide and 10 feet deep was located 100 yards inland of a landing beach. This trap was discovered to be heavily mined with this hemisphere antiboat mine. The enemy had made no attempt to place these mines according to a definite pattern. Some were buried completely, some half buried, and others lay exposed above-ground. But all were scattered haphazardly throughout the barrier.

Although indications on Leyte are that the Japanese have tended to use mine warfare to an extent greater than has been encountered in the past, preliminary reports indicate the Japanese are still lacking in adequate land mines and minefield doctrine. However, as the enemy improves his technique with time, U.S. troops must be prepared for more effective antipersonnel and antivehicle mining by Japanese units.


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