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"Amphibious Tactics Based on Experiences at Wake" from Intelligence Bulletin, April 1943

[Intelligence Bulletin Cover]  
The following report on Japanese amphibious tactics at Wake Island was originally printed in the Intelligence Bulletin, April 1943.

[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.]



Lessons learned by the Japanese in the land, sea, and air attack on Wake Island are contained in a recent enemy document. Of special note is the indication that the surrender of U.S. troops was hastened when a Japanese detachment got among civilian workers and began slaughtering them. Apparently the U.S. commander surrendered at that time to prevent further killing of these workers, realizing that surrender was inevitable anyway. The information given below has been taken from the enemy document, and is presented in a paraphrased and condensed form.


You must not use a plan of attack that has been used previously, because the enemy can anticipate our actions. And don't forget to take the enemy by surprise. This is absolutely essential.

Our method of operation must be determined only by the progress of the battle.

There are many cases where the soldier must value speed more than finesse.

The issue of victory lies in the constant maintenance of the offensive spirit. The great success of this operation (capture of Wake Island) was due, in the final analysis, to the constant display of this spirit by all personnel, without regard for their own lives.

It is necessary to train especially picked troops for the landing force.

In landing in the face of the enemy, it is necessary to utilize timely diversions and deceptive movements. If the diversion does not succeed in its purpose, it will hinder rather than help the subsequent operations. Because the diversion effort at Wake was carried out before the invasion force landed, the result was rather to alert the enemy than to deceive him. In view of this, similar operations in the future should be thoroughly prepared beforehand in regard to time, place, and method of attack. It also is essential to have thorough communication arrangements so that all units can be advised of any last-minute changes in our landing plans.

In case the landing is restricted to a very narrow front and there is no room for a diversion, you must either carry out a thorough bombardment before and after the landing, or make the landing in overwhelming force. If the attempt is made to land secretly (that is, using only motor boats and landing only small numbers at one time) on a place like Wake Island where landing is limited to a small area, it is evident that great losses will be incurred.

In the invasion of a strategic island, the command must be unified. The invasion forces consist of the Occupation Force, the Covering Force (naval and air), and also a force we may call "Cooperation." [Comment: This force is believed to be composed of reserves and unloading units.] The power of these forces cannot be developed fully if there is a lack of mutual understanding among them.


Because troops easily become scattered at night and control is difficult, execution of the operations must be made simple by detailed preparations. The following factors must be considered in deciding methods of operation, organization, and equipment:

a. Troops must be organized and equipped to fight independently during the daytime.

b. Remember that when the enemy's main batteries and other defense areas cannot be captured before daybreak, it is often impossible to get fire support from the ships during the day. [Comment: This shows a healthy Japanese respect for our shore batteries.]

c. At night, hand grenades and grenade throwers are extremely effective in silencing heavy guns. In day fighting, it is necessary to have machine guns and infantry cannon available for use.

d. All the first-line fighting strength must be landed at once. Quite often, motor boats used in the first landing become stranded and cannot be used for another trip.


If the beach is defended, it is absolutely essential to complete the landing before daybreak. In general, it seems that the earlier the landing time, the more effective it will be.

Although the Wake Island landing was effected 4 hours before sunrise, it turned out that the old saying "The hours of the night are short" was only too true. The landing originally was planned for execution at 2300 hours, but trouble in lowering the motor boats delayed us about iy2 hours. It is also necessary to allow extra time for approaching the shore and making the main landing.

Where there are fringing reefs, low tide is more advantageous for landing than high tide.

At night the enemy shells pass overhead; so damage is slight, although you receive a fierce shelling.

It is easy to mistake the landing point at night. The leading boat must approach at half speed or low speed until the island can definitely be seen from the large landing lighters.

To lead the boats in close formation within range of the enemy's defense guns is extremely dangerous; however, in landing operations in the dark on long swells around an island, and if the boats deploy 4,500 to 5,000 yards from shore, the lighters will find it extremely difficult to hold their course, and almost impossible to reach shore at the designated point. Although four lighters were led within 3,500 yards of the shore at Wake, none of them arrived at the appointed time or place. Two lighters which accompanied patrol boat No. 32 lost sight of her on the way because she increased speed. It is necessary for the leading boat to have a low-powered signal light on its stern for signaling to the rest of the boats.

At the time of landing, the normal speed of the patrol boat should be maintained. When the boats are proceeding shoreward at about normal speed, the enemy has extreme difficulty in aiming.

It is necessary to unload the boats very quickly after reaching shore, and a great deal of equipment should be made ready in the bow of the boat.


a. General Observations

The enemy forces are, after all, easily beaten. Although the U.S. force was numerically equal to the invasion force and was in a fortified position, it was defeated in a half day's fighting; so the conclusion is inescapable that the U.S. soldiers are at the beginning like lions, but at the end are gentle like virgins.

In the Wake Island operation, our landing force hardly fired a shot until daybreak, but used enveloping movements and hand grenades. In darkness, our use of rifle fire generally is damaging to us because it reveals our positions. Hand grenades and grenade discharges are extremely effective, particularly against enemy machine-gun positions, trenches, and so forth. There were some cases where enemy positions were surrounded from four sides, and use of the rifle might have caused casualties to friendly troops.

b. U.S. Tactics--How to Combat Them

(1) Attacking a Defense Position.--A diagram of a U.S. position is shown in figure 4.

Note that the Americans put two or three men out in front of their position. When we approach, they fire a volley and fall back in an attempt to lead us to their main body. (Study the diagram.)

[Figure 4. Diagram of attack on U.S. position.]
Figure 4. Diagram of attack on U.S. position.

To combat such positions, encircle them at night and fire on them heavily with grenade throwers and hand grenades. Immediately thereafter, rush the positions from the flanks and rear as well as from the front.

If the night charge fails, or if the opposing forces confront each other in the daytime, it is most effective to encircle the position and begin fighting with hand grenades and grenade throwers.

(2) How to Mop Up at Night.--The Americans usually post a sentinel, armed with a light machine gun, about 200 to 300 yards in front of their positions. After firing a burst, the sentinel skillfully withdraws to a nearby slit trench. When our forces have passed by, he opens fire and throws our rear into disorder.

Against these tactics, divide the troops into an assault force and a mopping-up force.

When the assault troops locate the enemy position, they will rush it. Remember to have scouts ahead of the assault force and to keep a sharp lookout to the rear.

The mopping-up force advances after thoroughly searching the trenches in the occupied area, throwing two or three hand grenades into likely hideouts. This force then occupies the ground taken and posts sentinels to secure our rear.

See figure 5, which is a diagram for mop-up methods.

(3) Attacking U.S. Positions in Heavy Brush.--On Wake Island, the enemy (U.S.) had numerous positions in the heavy brush area. These positions had many small machine-gun nests, with a few 50-caliber machine-gun nests as the backbone of the defense.

When attacking from the open ground in front, our troops received the sweeping fire of these machine guns, and our losses were great. When trying to attack the enemy's rear in the brush area, maneuvering was difficult because our troops were unacquainted with the terrain. Forces penetrating such positions should use special care not to become dispersed. They should surround the enemy and then use hand grenades, grenade throwers, and so forth.

[Figure 5. Japanese mop-up methods.]
Figure 5. Japanese mop-up methods.

(4) Attacking Skirmish Lines.--Although the Americans deploy in skirmish lines, they do not hold their ground. When we charge, they fall back and assemble in the vicinity of a defensive position, but they do not turn to the offensive—that is, they almost never counterattack. We should take advantage of this with all our power.

(5) Attaching Contractors Workers.--The U.S. contractor's workers have absolutely no fighting spirit. It is fruitful for us to raid those places where these workers may be found, as the first step in bringing about the surrender of the enemy. In the Wake operation, the success of one company's action as a flying column was the first step toward victory. [Comment: This unit apparently captured the contractor's workers and started slaughtering them.]


a. Destruction of land batteries with ship's guns or airplanes is difficult.

b. Direct cooperation between air and land forces is extremely effective, and the cooperation of light airplanes is essential (especially when we are weak in artillery and the enemy has powerful artillery, tanks, and so forth).

c. Detailed reconnaissance of enemy positions by airplanes appears to be extremely difficult.

d. It is sometimes hard to bomb air bases. It was difficult to see and bombard the Wake airfield with ship's guns because it is lower than the road around it.


When landing, it is necessary to devise measures to keep communication equipment from getting wet. In the Wake operation, communication between ships and the shore was impossible because the radios and telephones either got wet or received severe shocks. The rockets and signal pistols also got wet, and, although fired, they were difficult to distinguish from the enemy's machine-gun tracer bullets.

The methods of communication must be simple. In a landing operation carried out by a number of cooperating units, it is necessary to perfect communications so as to maintain close liaison. It is most important to have several simple, sure means of communications so that they will function regardless of the situation.


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