The Pacific War Online Encyclopedia

Friendly Fire

Photograph of heavy antiaircraft fire around friendly aircraft

U.S. Marine Corps. Via ibiblio.org

In the confusion of battle, it was not unknown for troops to fire on their own side by mistake. The American military referred to this as friendly fire, as distinct from enemy fire. Since there is nothing friendly about it, friendly fire resulting in casualties has sometimes been called fratricide. Commonwealth troops sometimes referred to it as own fire or self fire. The term blue on blue dates from long after the time frame of the Pacific War.

Certain combat activities were particularly prone to friendly fire incidents. When patrolling in dense jungle, it was difficult for infantrymen to keep track of the members of the patrol. Contact with the enemy usually led to fierce firefights, and in the confusion it was easy to fire by mistake at one's own man, or to fire at an enemy but hit friendlies who had blundered into the line of fire. Night operations suffered from the same dangers. Because of the Japanese fondness for night operations, most Allied troops adopted a policy of staying in their foxholes at night and assuming anything up and moving around was the enemy. The U.S. Marines used passwords containing the letter 'L' (which was difficult for most native Japanese speakers to pronounce) to help identify their own in the dark. After a number of nisei interpreters were shot by American troops who mistook them for enemy infiltrators, a policy was adopted requiring that every nisei be accompanied by a Caucasian military policeman.

Long-range weapons also posed a risk of friendly fire. Artillery had to be careful not to drop short rounds on friendly troops. When in doubt, the artillerists fired long. In some cases, artillery was deliberately called down on friendly positions that were being overrun, on the theory that the defending troops were dug in and would take less punishment than the attackers. Often the forward observer himself made this difficult decision, calling down fire on his own position, as happened during the night fighting around Henderson Field during the Guadalcanal campaign.

Ground support led to many friendly-fire incidents. The aircraft flying ground support had only seconds to identify their target, drop their munitions, and get clear to avoid return antiaircraft fire. It is no surprise that mistakes happened, even when ground forces were careful to mark the enemy positions with smoke. Such incidents became less common as the war progressed, but they were never entirely eliminated.

It was not just ground forces that suffered from friendly fire. Amphibious command ship McCawley was sunk by U.S. PT boats that had been told there would be no friendly ships in the area that night. There were numerous incidents of naval forces firing on their own ships by mistake during night actions, as well as situations when a naval force hesitated and lost a tactical opportunity from fear of firing on its own ships. During the Naval Battle of Guadalcanal, both situations occurred in the same battle.

Ships also suffered from friendly fire from aircraft, which often had difficulty correctly identifying ships from high altitude. Submarines seemed particularly prone to this kind of attack early in the war, but even surface task forces were sometimes attacked by their own side, as occurred during the Battle of the Coral Sea, when an Allied cruiser force was attacked by American land-based bombers (fortunately without any casualties.)

Aircraft caught it in return. Fighters had to be careful about engaging enemy aircraft close to their own forces, whose antiaircraft gunners often fired on both aircraft with fine impartiality. Early in the war, many Allied aircraft had identifying insignia containing red circles; these were quickly changed so that they could not be mistaken for the distinctive Japanese hinomaru or Rising Sun disk. Aircraft also took friendly-fire casualties from each other, particularly at night. There were incidents where aircraft on low-level attacks followed too closely behind each other and an aircraft was caught in the explosions from the preceding plane's bombs. The danger from one's own antiaircraft fire was not restricted to aircraft; antiaircraft fire could easily hit one's own surface forces. Some antiaircraft rounds were designed to deliberately self-destruct at a fixed range to avoid this. As American fleets grew larger, fire control doctrines were worked out to ensure that ships were able to concentrate their fire without hitting friendly aircraft or each other.

The Allies developed Identification Friend or Foe (IFF) equipment for their aircraft as the war progressed. This gave a distinctive signal on radar that identified the aircraft as friendly. Early systems were simply a passive dipole antenna that enhanced the aircraft reflection, but active systems were in use by the end of the war that send a coded signal when triggered by friendly radar. These helped significantly in reducing friendly fire incidents. The Japanese Navy and Army could not agree on a common system for IFF, rendering Japanese IFF all but useless.

Submarines were at risk whenever they operated in areas patrolled by their own ships and aircraft. Seawolf was sunk by U.S. destroyer escort Richard M. Rowell when she wandered out of her safe lane and her frantic efforts to send a recognition signal by sonar were misunderstood. It worked the other way, too: Salvage ship Extractor was sunk by Guardfish when a message ordering her out of the submarine's operational area was too garbled to decipher. Submarine sinking a friendly ship might have been a truly serious risk had submarines actually operated with the fleet as envisioned in prewar tactical doctrine.

Avoiding friendly fire was largely a matter of training. Lax fire discipline among green troops was evident in the New Georgia campaign and accounted for 12 percent of all casualties. Sadly, a disproportionate share of these were fatal, since most friendly-fire casualties were inflicted at close range with rifles or machine guns, which are particularly lethal. Bergerud quotes one infantryman:

Dysentery was rampant on Guadalcanal. It is a miserable malady ... The desire to relieve yourself is just tremendous. At night, what do you do? We had passwords, but the Japs were all over and guys were quick to shoot. So do you stay in the hole or go out for a minute and risk getting shot. Those were the alternatives. Many people stayed in their hole, but I'm afraid many of the men shot after dark had their pants down. It was amazing how many ways you could get hurt in World War II.

Front-line troops used passwords to identify each other at night, but this was not foolproof (Sloan 2005):

... "Who goes there?" a Marine yelled. "Give the password, damn it!"

"Chevrolet," a voice responded. "It's Chevrolet."

"That's yesterday's. Give me the password for today, or I'll shoot you, so help me God."

"No, man, don't shoot. I swear I thought it was Chevrolet. I can't remember nothin' anymore, but it's me, for Chrissake!"

"You got one last chance," the first Marine said grimly. "What's the damn password?"

"Chevrolet. That's all I know."

A rifle cracked in the darkness, followed by a brief silence. Then Womack heard a pained but surprisingly calm voice: "Well, you son of a bitch, I hope you're satisfied now. You did shoot me."

It was soon established that the injured man was, indeed, a Marine who'd simply forgotten the password, or maybe never heard it in the first place....

Friendly fire was also a problem among the poorly trained troops of X Force in Burma. The Chinese 150 Regiment sustained 671 casualties from friendly fire in two days in May 1944.

Related to friendly fire was the danger of collision between friendly aircraft or ships. There were a number of such incidents during the war, including the ramming of Indiana by Washington on 1 February 1944 and, astonishingly, the underwater collision of Flounder and Hoe on 23 February 1945 while operating in separate patrol areas deep in Japanese-controlled waters.

Another related danger was circular torpedo runs. If a torpedo's gyro failed, or it was rolled by a shell burst or large wave, it could begin running in a circle with the obvious danger of coming back to hit its own launch platform. At least two American submarines succeeded in sinking themselves in this manner.

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