Since Manila is located within an earthquake zone, its buildings are necessarily of very strong, heavy construction gauged by American standards. As an example of this, the Finance Building in downtown Manila was so constructed that, as the lower portion of the outside walls disintegrated under the direct fire of our artillery, the walls and roof settled and the structure bent, rather than collapsed. Intramuros was surrounded by a wall varying in thickness from ten to forty feet, and contained tunnels and excavated positions for gun emplacements. Projecting from the wall were bastions heavily organized. The entire area was medieval in structure and its defense combined the fortress of the Middle Ages with the fire power of modern weapons. The Japanese used· all types of earthquake-proof structures--private homes, churches, schools and government buildings -as isolated strong points. Machine guns and anti-tank weapons were sited within the buildings in such a manner as to protect approaches. The positions· were improved by conventional defensive installations. Concrete structures were strengthened by sand bags. Entrances, stairways, windows and corridors were sandbagged or reinforced by concrete, and often protected by barricades of such construction that they withstood numerous hits from tanks firing 75 and 105mm guns at point blank ranges. Small rifle and machine-gun slits were chipped in walls. In several cases these slits were found to have the drawback of being very narrow apertures which limited fire to a single passageway; little thought seems to have been given to small arcs of traverse and search which, in some cases, would have been desirable. There were alternate positions for automatic weapons throughout the buildings. Man-made tunnels connected the rear and side with outlying bunkers. Barbed wire entanglements were employed inside and outside of buildings. In adjacent grounds there were foxholes of the standing type. The enemy's main defensive organization was usually on the ground floor. In some instances troops were deployed in upper stories and on roofs to support the main defensive positions; these troops carried on the fight after our forces had seized the lower floors. Inside buildings were found bomb shelters constructed of a large cement culvert pipe, with one-half inch steel sheeting as a base for the roof, over which sandbags were stacked.

Approaches to buildings were also blocked by obstacles and mines covered by rifles, machine guns and anti-tank weapons, which were normally protected by heavily sandbagged pill boxes. Full advantage was taken of stone walls around houses and buildings to add to delaying obstructions.

Typical of the tenacious defense of buildings was the action centering around the Manila Hotel. After our troops occupied the upper floors of this structure following an all night battle, the enemy re-occupied the lower levels. The following morning the Japanese retired under pressure to an air raid shelter located in the basement. An estimated 200 of the enemy perished upon the sealing of the shelter entrance.

Annex 5 - Sketch No. 18 - Denying the Approach to Quezon Bridge

Charts and pictures illustrating building defenses are attached as Annexes 5 to 25. Particular attention is invited to Far Eastern University, (Annex 5) and to Rizal Stadium (Annex 6). The purpose of the defense of the University was to deny us the use of Quezon Blvd. and its approach to Quezon Bridge. No attempt was made to coordinate the defense of this position with Bilibid Prison or with Santo Tomas University, several blocks to the east. Enemy troops in Far Eastern University were estimated at not less than 200. The position was reinforced by sand bags and wooden barricades. The machine guns at the northwest corner of Quezon Blvd. and Azcarraga Ave. were emplaced in pillboxes of reinforced concrete and were additionally covered by three bands of barbed wire strung on steel rails embedded in concrete. The defense within the building was typical of that found in the Manila area.

Annex 6 - Blocking the Advance on the South Side - Rizal Stadium & Harrison Park Area

The Rizal Stadium area was two blocks square and consisted of four main athletic structures within a large cement stadium. A drainage ditch 15 feet wide and 10 feet deep along the entire  east side of the stadium provided a natural tank trap. This approach was further protected by a concrete wall 15 feet high and 2 feet thick. Open fields to the north and west of the Stadium and a wide avenue (Vito Cruz) on the south afforded the enemy excellent fields of fire. The defense was centered around two buildings on the south side of the area, the Ball Park and the Coliseum. In each building all doors, windows and passageways were barricaded with sand bags. Small rifle slots had been chipped in the walls and street approaches were heavily mined.

c. Streets:

Streets were blocked by all types of obstacles. Intersections were barricaded and further defended by automatic and anti-tank weapons sited to cover streets approaching the intersection. Approximately fifty barriers were removed between 7 February and 3 March in the Paco, Ermita and Intramuros Districts of South Manila. Annex 26 shows an approximate reconstruction of the installation at one typical street intersection. In this particular case there was a supply of railroad car axles nearby; these were set upright in the pavement to serve as barricades.

Annex 21 - Street and Building Organization

2. Other Fortifications.

Pillboxes in the Manila area showed little departure from· the conventional type.

Annex 27 illustrates a type frequently encountered. Essentially, the materials used-concrete, metal, wood and sandbags-were standard. The thickness of the pillbox walls ranged from inches to several feet. Some had the inside walls sandbagged to a depth of several feet; thus reducing fragmentation within the confines of the positions.

The pillboxes and their immediate approaches were provided with obstacles, usually consisting of barbed wire entanglements, designed to force our troops into fire swept areas and to prevent the close approach of infantry and engineer assault groups. Connecting trenches, both covered and uncovered, were a normal part of the defensive scheme. (See Pillbox and Connecting Trench - Annex 28). In some cases, tunnels led from the pillboxes to the interior of nearby buildings and other pillboxes. These connecting trenches and tunnels permitted the rapid and unobserved movement of troops to or from threatened areas. Some of the pillboxes had limited fields of fire, but, when incorporated into the general scheme of organized defense, covered each other with well directed fire.

Those having limited fields of fire were in positions that did not permit the opening of fire until the assaulting troops were fairly close. Such positions, while possessing this disadvantage, had the merit of being protected from the fire of weapons in the hands of attacking troops until they were at very short ranges, as is illustrated in Annex 29.

Following their doctrine of utilizing camouflage to the utmost, the Japanese found the destroyed. areas of great value in providing material with which to conceal their positions. The debris from shattered buildings furnished additional protection to pillboxes inasmuch as it acted as a buffer, when piled around and on top of the positions, by dissipating the effect of exploding shells and demolition charges.

b. Barricades:

Like other defensive installations discussed, barricades were constructed to meet the needs of the situation as it developed. A barricade in the form of steel rails embedded in the ground and .standing six to eight feet high, irregularly spaced from two to three feet with barbed wire strung between, was commonly encountered. Anti-tank and anti-personnel mines were interspersed throughout the barricade itself and in front of it. Others encountered were of the "hedgehog" and "Cheval de Frise" types. Some barricades were made by merely overturning automobiles and trucks. In other instances heavy factory machinery was moved into the streets and there firmly embedded. Fuel drums, into which steel rails or hardwood timbers were placed and then packed with cement or earth were frequently found. Here, too, barbed wire and smooth wire was used. One kind of anti-tank barricade was composed of fuel drums set upright and arranged in two or more columns. The space between these columns was then filled with dirt, as were the drums themselves, and the areas in front of the barricades were sown with mines. (Annex 32). Anti-tank ditches and shell craters used as such were employed extensively.

Within buildings, corridors were heavily barricaded with ordinary household and office furniture. Other obstructions in the form of walls arranged in staggered positions were set up inside the passage ways. These walls, usually wooden forms filled with dirt, were from three to four feet thick and from seven to ten feet high, and provided enough clearance between the top of the wall and the ceiling to permit the lobbing over of grenades. (Annex 33).

Although the barricades encountered in the Manila City area were frequently well made, many were hastily improvised. Despite the fact that the troops committed to the defense of the city were a conglomeration of different branches and services and were equipped with comparatively little in the way of heavy construction material and machinery, an efficient system of barricades which facilitated stubborn defense was devised.

The ingenuity demonstrated in the utilization of means at hand for obstructions indicates that with more suitable materials the Japanese will in future operations oppose a more formidable type of barricade to attacking Allied troops.

c. Minefields:

Minefields were used extensively by the enemy throughout the Manila area. Controlled and uncontrolled minefields as well as combinations of both types were found on roads, bridges, in the vicinity of barricades, and in open lots. Most minefields were covered by fire, but in many cases the enemy withdrew or was forced to evacuate from covering positions. No regular pattern within minefields was noted, and the minefields themselves were liable to be encountered anywhere. In general, the fields were poorly camouflaged, many mines being only partially buried and easy to locate.

There was apparently no organization in the choice of types of mines, for all available explosives were freely used and indiscriminately mixed. Naval beach mines were most common, and were followed in number by converted aerial bombs. These types were frequently found together, in the proportion of two beach mines to one aerial bomb. In addition artillery shells, mortar shells, depth charges were often used as mines.

As a rule, depth charges were prepared for electrical detonation, with control wires leading to a concealed position. These were also found placed on end six to eight inches below ground level. On top of the depth charge was a ceramic or yardstick mine flush with the ground. In fields and on grassy road shoulders, depth charges with ceramic mines and trip wires, either single or interconnected, were met. Fifty-five gallon drums were found to contain depth charges in conjunction with ceramic mines. This combination was most often used in road blocks.

Ceramic mines were frequently trip-wired, and yardstick mines were scattered on road surfaces or placed above buried 100 pound aerial bombs. In other instances, aerial bombs with a nose impact fuse set close to the surface were found; a pressure of only fifty pounds was sufficient for detonation.

Annex 34 shows a typical minefield in the New Manila Subdivision. North-south streets were prepared throughout with scattered mines. Two cross streets were mined; extensions into fields at the flanks included a potato patch, in which was found one of the few pattern fields laid out by the enemy. Another field at approximately the center of the subdivision, in the unused portion of a block, consisted of scattered depth charge ceramic mine combinations, all independently trip-wired with a set of easily detected yellow wires.

Annex 35 shows a minefield on Vito Cruz between Luna and Taft A venues which illustrates the tendency to mix all available types. The three ceramic mines to the left of the anti-tank ditch were concealed under galvanized iron sheeting. The group of depth charges were all interconnected and wired to the blockhouse for controlled detonation.

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