Photograph of Kachin guerrillas

U.S. Army Center of Military History

Guerrillas are irregular military forces that operate in enemy territory through stealth and surprise. They typically live off the land and are often indigenous to the area in which they operate.  They are distinct from paratroops, which are regular forces that operate as elite light infantry once landed; from Commando and Marine Raider units, which were regular forces that engaged in deep raids but were based in friendly territory between operations; and from the Chindits, which were regular forces the operated much like guerrillas but were not indigenous and were regularly resupplied (and evacuated their wounded and sick) via the air.

The Second World War was almost entirely a conventional high-intensity conflict, with guerrilla insurgencies playing only a secondary role. However, guerrillas in Europe and the Pacific occasionally made a significant contribution to the outcome of conventional battles and campaigns. Guerrilla movements played a more significant role in the postwar world, particularly in southeast Asia, where the surrender of the Japanese left a power vacuum that was successfully exploited by nationalist guerrilla movements.

Guerrilla warfare closely resembles the internecine tribal warfare of the earliest human cultures, making it arguably the oldest form of warfare. There is anthropological evidence that early tribal warfare took the form of surprise raids on enemy villages in which quarter was neither asked nor given, and that the average tribal society lost as much as 0.5% of its population in combat every year. The earliest states (such as Akkad in the 24th century B.C.E.) found themselves waging counterinsurgency warfare against the surrounding tribal cultures. Guerrillas continue to be closely associated with insurgencies in the 21st century.

Most guerrilla campaigns fail. Those guerrilla insurgencies that have been most successful have usually received outside assistance, as did most of the guerrillas that fought against the Axis during the Second World War. The combination of a guerrilla campaign with a conventional military campaign is sometimes called "hybrid warfare", though this label was invented long after the time frame of the Pacific War.

Because guerrillas were irregular forces, they generally could not claim lawful combatant status and had no protection under the Geneva and Hague Conventions. Lawful combatants were required to be under the command of a legitimate sovereign government, to fight in accordance with the laws and customs of war, and to wear distinctive insignia, visible from a distance, when engaged in combat operations. Guerrillas generally did not wear such insignia and did not have a regular chain of command. However, this distinction could become blurred, as when Filipino guerrillas improvised American insignia and established contact with MacArthur's headquarters in Australia. Such guerrillas arguably became lawful combatants (and could be classified as militia.) However, the distinction was largely moot: The Japanese treated all prisoners of war brutally, and they usually executed Allied personnel caught behind Japanese lines, whether or not they were in uniform. 

In some cases, the treatment of guerrillas as bandits was not unjust. Under wartime conditions, irregular forces sometimes felt compelled to take what supplies they could from the local population whether the local population were willing or not, and it was inevitable that some genuine bandits would seek justification as "freedom fighters." This was a particular problem in rural areas of occupied China, where kidnapping for ransom became distressingly common.

Guerrillas often had close ties to underground movements. The distinction is that guerrillas carried arms openly while underground movements operated clandestinely in the midst of the enemy. Most underground movements focused on espionage and distribution of propaganda, but sometimes engaged in sabotage as well.

Guerrilla Tactics

Because guerrillas are generally poorly trained, poorly armed, and inadequately supplied, they cannot hope for success by using ordinary military tactics. Instead, guerrillas engage in hit and run raids designed to force the enemy to commit large bodies of troops to garrison duty and the protection of lines of communication. From a military standpoint, guerrillas are most effective when they have some contact with regular forces fighting the same enemy, for whom they can provide valuable intelligence and from whom they can be resupplied.  Guerrilla forces that attempt to engage in positional warfare usually suffer heavily, as the Chinese Communists did as a result of the Hundred Regiments Offensive. Once the Japanese recovered from their initial surprise, they inflicted very heavy casualties on the Communist guerrillas.

Guerrillas are not without their strengths. Because they usually are able to live off the land, they do not have lines of communications to protect. They are usually more familiar with the local terrain than their enemies, and, if they can count on the support of the local population, they usually have a decided intelligence advantage. They are also more mobile than more heavily equipped regular troops. All these factors work in favor of a strategy of hit and run raids on enemy weak points.

There is always a large political element to effective guerrilla operations, which seek to win the hearts and minds of the local population, on whom they depend for most of their provisions and from whom they seek to recruit.

The contrasting efforts by the Chinese Communists and the Kuomintang to use guerrilla tactics in north China illustrate how guerrillas should, and should not, operate.  Notwithstanding costly setbacks like the Hundred Regiments Offensive, the Communists were reasonably successful as guerrilla forces, largely because they well grounded in the peasant population. This provided a huge pool of new recruits. The Kuomintang, by contrast, were led by Army officers who lacked rapport with the peasants and were thus unable to replace their losses. The Kuomintang guerrillas also were slow to abandon positional warfare and large-scale assaults.

Antiguerrilla Tactics

Conventional military forces that attempt to come to grips with guerrillas using conventional military tactics usually find themselves punching into empty air. It is nearly impossible for a conventional force to compel a guerrilla force to give battle. "Search and destroy" tactics rarely destroy many guerrillas, but can alienate large numbers of civilians through their collateral damage. A better approach is "secure and hold" tactics that put the conventional force in the role of protecting the local population. A sufficiently ruthless and determined conventional force can devastate guerrilla base areas, eliminating their ability to live off the land and enhancing the contrast with the relative safety of the secured areas. A successful counterinsurgency also requires that the counterinsurgents be able to cut off the guerrillas from outside support. The Japanese never fully accomplished this in any of the areas they occupied during the war.

The Japanese countered the Chinese guerrillas with the Three Alls: "Kill all, burn all, loot all." At least 30 antiguerrilla campaigns on a multidivisional scale were carried out in north China between 1941 and 1945. Operating areas were devastated to leave the guerrillas no shelter or means of sustenance. The Japanese adopted a "point and line" deployment in which they garrisoned the major cities and the lines of communication between them but left the countryside unoccupied except for periodic sweeps. "Point and line" was a form of "secure and hold", but the sweeps were a fruitless form of "search and destroy" that, together with the Three Alls, alienated the Chinese civilian population. Chinese puppet troops were used in areas well behind the front lines to man checkpoints every li (0.3 mile or 0.5 km) on major roads and watch towers every mile. The roads were lined with bamboo barricades, and puppet troops conducted dawn sweeps through fields using dogs.

The Japanese made use of radio direction finders, in the Philippines and elsewhere, to pinpoint guerrilla radio transmitters. The Japanese would then sweep the area, sometimes with air and naval support. Japanese antiguerrilla activities in the Philippines ramped up significantly after June 1943, including a sweep of Mindanao for guerrilla forces that alienated the population of the island.

Conventional armies must allocate sufficient troops to police their rear areas. Where guerrillas are not yet active and the local population not particularly hostile, it is estimated that one soldier per 356 civilians is adequate. Where guerrillas are active, the ratio may need to be as high as one soldier per 40 civilians. Thus, under the most optimistic of assumptions, the number of troops required for security duty in wartime India would have been about 840,000 men, which goes a long way towards explaining why the Indian Army was never able to provide the number of divisions Churchill thought it ought to have been able to provide. In the case of China, with a very hostile population and active Communist and Kuomintang guerrilla movements, some 10 million troops would have been required to guarantee pacification of the countryside. Even with large numbers of puppet troops, this was completely beyond the capacity of the Japanese Army, which goes a long way towards explaining the Chinese quagmire.

A successful counterinsurgency also requires highly disciplined troops who will not respond to guerrilla attacks by destroying everything within sight. Conscripted troops are particularly unsuitable for waging a counterinsurgency, which suggests that the mass armies that fought for the major powers in the Second World War were particularly ill-suited for dealing with the numerous guerrilla movements that sprang up during the war. From this narrow perspective, it was the good fortune of the Allies that, for the most part, it was the Axis doing the occupying of hostile territoryearly in the war.

Successful counterinsurgency also requires mastery of psychological warfare. Gerard Templer, who would wage a model counterinsurgency in Malaya in the 1950s, declared that "The shooting side of the business is only 25% of the trouble, and the other 75% lies in getting the people of this country behind us" (quoted in Boot 2013). He also said that "The answer lies not in pouring more troops into the jungle, but in the hearts and minds of the people" (ibid.) This lesson was never learned by the Axis, and it was forgotten by the French and the Americans in postwar Indochina.

Allied Guerrillas

Philippines. Probably the most active and effective guerrilla movement of the Pacific War was the Filipino guerrilla insurgency. Many of these guerrillas were former regular Philippine Army troops who had escaped the Japanese dragnet by blending in with civilians. Some were directed by American officers who had likewise escaped, and many eventually made contact with MacArthur's headquarters. For example, on 3 January 1943, Captain Ralph B. Praeger, who had escaped from Bataan into central Luzon, made radio contact with MacArthur, reported that he had organized a force of 5000 guerrillas, and asked for an arms drop with which to begin a sabotage campaign. MacArthur instructed him to restrict has activities to intelligence gathering to avoid Japanese reprisals against civilians. However, Praeger's men could not be persuaded to refrain from ambushing Japanese soldiers when the opportunity presented itself.

Another American guerrilla leader in the Philippines was Wendell Fertig, a mining engineer who held a reserve commission and was called to the colors before war broke out. He had escaped from Corregidor to Mindanao by aircraft to organize engineering activities under Sharp, then escaped again following Sharp's surrender. Fertig organized a force of several thousand guerrillas on Mindanao, mostly from former Filipino Army recruits who had slipped away to their homes at the time of Sharp's surrender. These men had hidden their arms, but recovered them to fend off bandits emboldened by the collapse of the Philippine Constabulary. Now rearmed and organized into vigilante groups, they were obvious targets for recruitment as guerrillas.

Filipino guerrillas received instructions and supplies (dropped by air or delivered by submarine) and, in return, sent back a considerable volume of sometimes very valuable intelligence. Much of the direction of the Filipino guerrillas was carried out through "Chick" Parsons, a Navy reserve lieutenant commander who had spent most of his adult life in the Philippines. Parsons was fluent in Spanish and could communicate in two native dialects, was unusually well acquainted with the southern islands, and was sufficiently short and dark to blend in with the native Filipinos. After war broke out, he was registered as the Panamanian consul as a legal fiction to facilitate the reflagging of Danish freighters, and he continued to pass himself off as a Panamanian diplomat after the Japanese occupation. He and his family were repatriated in October 1942 in exchange for Japanese civilians in Latin America, during which he smuggled out extensive intelligence on the Japanese occupation at great personal risk. MacArthur requested his services, and Parsons became head of "Spyron" (Spy Squadron, a word play on Naval jargon for type squadrons), making repeated trips to the Philippines by submarine or (late in the war) Catalina to coordinate guerrilla activities. 

There was also an active underground movement in the Philippines which maintained close ties to the guerrillas. Several of the leaders were Americans who had found ways to establish false identities for themselves as citizens of Axis or neutral countries. For example, Claire Fuentes, an American citizen who had worked as an entertainer in Manila, managed to obtain false papers from the Italian consulate identifying her as a Philippine citizen of Italian birth. Fuentes established Club Tsubaki, an upscale resort for Japanese officers, from which she worked for the underground as "High Pockets". In May 1945 the Kempeitai intercepted one of her couriers, a Russian expatriate, carrying incriminating letters. Fuentes was imprisoned and tortured but refused to confess to any activites the Japanese did not obviously already know about, and she somehow survived to be liberated in 1945. Another of Fuentes' couriers was Father Buttenbruck, a German Catholic priest sympathetic with the Allied cause, who was eventually executed by the Japanese.

One of the more prominent members of the underground was José Ozámiz y Fortich, a member of the Philippine Senate who joined the collaborationist government but maintained contact with the guerrillas. After meeting with Fertig and Parsons in May 1943, his activities increased, but he was betrayed by members of the makapili and beheaded in February 1944.

The Japanese countered the underground with a network of agents under the Kempeitai. Graduates of Nakano School operated under civilian cover, including the "Institute of Natural Science", a false front for the main Nakano headquarters in Manila. Another source of intelligence was "Rita", a German agent of French descent who was fluent in Tagalog and several other languages and became known as the "Mata Hari of the Orient." Rita participated in brutal interrogations in Manila during the Allied battle for the city, escaped to northern Luzon, but died under mysterious circumstances before she could return to Japan.

The Japanese initially made little effort to round up American civilians in the back country of the Philippines. However, in January 1944,the Japanese published an edict that any American who did not turn himself in by 25 January would be summarily executed. Thirteen civilians on Panay were executed even before the deadline, and Parsons began a sizable effort to evacuate the remaining American civilians by submarine. Some 450 civilians were successfully brought out. They did not include Parson's mother-in-law, who was beheaded by the Japanese on charges of guerrilla activities in August 1944.

The Filipino guerrillas established covert contact with Allied prisoners of war at Cabanatuan, and were able to smuggle vitally needed food supplies into the camp that doubtless saved many prisoners from starvation. During the American reconquest of the Philippines, Parsons was able to warn Filipino civilians to evacuate from areas schedule for prelanding bombardment. Parsons also got word back to MacArthur that a large Filipino civilian population was being held in Tacloban by a small Japanese garrison, and the prelanding bombardment was modified to spare the city. Filipino guerrillas carried out reconnaissance activities ahead of the advancing regular troops.

Not all Filipino guerrillas were pro-American. Some were Communist insurgents who were almost as hostile to the Americans as to the Japanese, and who continued their insurgency after the Japanese surrender.

Burma. Another successful guerrilla movement was organized by the British and the American OSS Detachment 101 among the Kachin tribesmen of northern Burma. The Kachin were hostile to the Burmese and Thai ethnic groups aligned with Japan and had suffered a number of atrocities at the hands of the Japanese. They were organized into the Northern Kachin Levies at Fort Hertz and became very successful at harassing isolated Japanese outposts, at gathering intelligence, and in serving as guides to regular Allied forces.

Detachment 101 also organized guerrilla movements among the Karen, an ethnic minority in southern Burma that suffered from mistreatment by Burmese Nationalists. Karen guerrillas harrassed the Japanese forces in the Shan States of eastern Burma to prevent them from interfering with Slim's drive to Rangoon in 1944. However, the Japanese responded with vicious reprisals. One group of two hundred Karen guerrillas was led by Hugh Seagrim, a British officer, who decided to give himself up in order to spare the Karen tribes further reprisals. He was executed, but the reprisals continued.

Malaya. Ethnic Chinese were active in organizing guerrilla operations against the Japanese in some parts of southeast Asia. For example, Lim Bo Seng was an ethnic Chinese from Singapore who helped organize a guerrilla force in Malaya. Prior to the outbreak of war in the Pacific, he had helped organize anti-Japanese boycotts and raise money for the Kuomintang from the ethnic Chinese community. The Malayan People's Anti-Japanese Army, a Communist force with connections to the Chinese Communists, was also active in Mayala. Postwar the MPAA would become the Malayan Races Liberation Army and turn on the British, who crushed the movement using a counterinsurgency strategy that is still studied as a model in the 21st century. However, the counterinsurgency succeeded only because the British promised self-government to Malaya once the "Malayan Emergency" was over, a promise that was kept in 1957. Ironically, one of the most effective leaders on the military side of the counterinsurgency was "Mad Mike" Calvert, who had led a column of the Chindits in Burma.Calvert carried out long range penetration missions in Malaya assisted by Dyak headhunters from Borneo, who had carried out guerrilla operations against both sides at different times during the Pacific War.

China. In one of the oddest divisions of responsibility of the Pacific War, the U.S. Navy ran a significant guerrilla operation, the U.S. Naval Group China. The "Rice Paddy Navy" was nominally responsible for weather observations in occupied territory (much of the weather of the western Pacific is shaped over China) and also for coast watching operations. U.S. Naval Group China ran a weather station in inner Mongolia that ws protected by a force of 200 guerrillas, who clashed with a Japanese armored column on 15 May 1945. Another section of U.S. Naval Group China trained guerrillas operating against communications in the Yangtze river valley. The head of the U.S. Naval Group China, Commander Milton E. Miles, worked closely with Tai Li, chief of the Chinese Bureau of Investigation and Statistics, who has been variously described as the Chinese Himmler or the Chinese J. Edgar Hoover.

In what would eventually become a painful irony, the Communist underground in French Indochina under Ho Chi Minh received encouragement and support from the OSS for their guerrilla campaign against the Japanese. Postwar these same guerrillas would drive out the French and later the Americans.

Much was claimed for the guerrilla activities of the Chinese Communists in northern China, but the weight of evidence is that the Communists engaged in very little direct action against the Japanese during the Pacific War. Instead, the Communists build up their strength in rural areas behind Japanese lines and prepared for the civil war that would inevitably follow the defeat of Japan.

Netherlands East Indies. The Dutch made several attempts to insert agents into the Netherlands East Indies, but all were captured and executed almost as soon as they landed. The native Indonesians were inclined to side with the Japanese, though as the war progressed, they were increasingly disenchanted and an active native guerrilla movement took hold. As with the Communist guerrillas in the Philippines, these were almost as hostile to the Dutch as to the Japanese. There was also guerrilla activity in Borneo among tribesmen alienated by Japanese brutality, such as the Dyak, who helped hunt down Japanese who escaped to the interior following the Australian landings at Brunei.

Manchuria. The Russians ran an extensive guerrilla operation from camps across the border from Manchuria. Several thousand Chinese Communists were trained by the Soviet Far East Intelligence Group, and along with harrassing Japanese forces, these guerrillas provided the Russians considerable intelligence on Japanese dispositions. This doubtless contributed to the decision to risk pulling troops west to fight the Germans in late 1941, as well as guiding preparations for the Manchuria offensive of August 1945. To preserve Russian neutrality, the guerrillas trained in great secrecy, isolated from any Russians other than their instructors, but were otherwise treated as well as the Russians could manage.

These Soviet-sponsored guerrillas were eventually organized into the 88 Independent Brigade, with four Chinese and one Korean battalion. The Korean battalion was commanded by Kim Il Sung, future dictator of North Korea. These troops were used primarily for security duties once Russia intervened in the war.

Japanese Guerrillas

Japanese guerrilla activities were limited to "fifth column" operations in southeast Asia during the Centrifugal Offensive. Their extent and impact was greatly exaggerated by the Allies at the time, perhaps to excuse Japanese military success; but there is little doubt that fifth columnists existed and sometimes had a significant effect on operations. Pro-Japanese guerrillas appear to have been most active at Hong Kong and in Burma. British officers in Malaya reported that Japanese troops infiltrated their lines disguised as civilians and set off firecrackers behind the lines to panic inexperienced troops.

Later in the war, when the Allies began driving the Japanese back,  it was not uncommon for Japanese soldiers to hold out in wilderness areas behind Allied lines. However, these were regular troops in uniform who were still technically under the authority of the Emperor, so they did not qualify as guerrillas, and those who eventually gave up were treated as prisoners of war. However, a few of these soldiers remained at large after the general surrender. Some either did not know or refused to believe that Japan had surrendered, and were generally repatriated without fuss when they did finally turn themselves in, sometimes decades after the surrender. A few larger bodies of troops had to be coaxed into surrendering by representatives of the Emperor sent out under Allied direction to see that the surrender terms were effectuated.

The Japanese raised 5 Guerrilla Unit, also known as Mori Special Force, in Burma to raid the Allied fuel pipeline being laid along the Ledo Road. It is not clear whether this would best be described as a guerrilla unit or as a special force, but before it could complete its training, it was committed to raiding the airfields around Meiktila during the seige of March 1945 and largely destroyed.

As it became increasingly clear that the home island were no longer safe from invasion, Nakano School began preparing for guerrilla warfare. Some Nakano men were assigned to the Ryukyu Islands, but immediately stood out among the indigenous people as Yamatojin, Japanese from the home islands. Nakano men also lead small units in northern Okinawa to harass the Marine advance. Meanwhile, Nakano School graduates who had specialized in strategic intelligence were redeployed to Kyushu to help meet the expected Allied invasion, since strategic intelligence seemed increasingly irrelevant. These were organized into Kirishima Unit, and their commander, Captain Kishimoto Iwao, issued "A Reference for Guerrilla Warfare in Japan" based on Chinese and Soviet Communist documents on guerrilla warfare. Some 5000 guerrillas were trained on Kyushu. Meanwhile Yashima Unit was organized to play a similar role in the Tokyo area. Izumi Unit was organized in great secrecy to be a guerrilla unit to contest the Allied occupation of Japan. The men of the unit slipped quietly back into civilian roles in their home towns with orders to carry out a terror campaign against the occupying forces and Japanese collaborators.


Allen (1984)

Bergerud (1996)

Boot (2013)

Breuer (2002)

Chang and Holliday (2005)

Drea (2009)

Dunlop (1979)

Ferguson (1980)

Gilbert (1989)

Hastings (2007)

Mercado (2002)

Mitter (2013)

Morison (1959)

Peattie et al. (2011)

Ramsey and Rivele (1990)

Tamayama and Nunneley (2000)

Thompson (2005)

Wise (1968)

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