Guerrillas

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.

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 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.

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

Allied Guerrillas

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. These 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. During the American reconquest of the Philippines, these guerrillas carried out reconnaissance activities ahead of the advancing regular troops. Other Filipino guerrillas were Communist insurgents who were almost as hostile to the Americans as to the Japanese, and who continued their insurgency after the Japanese surrender.

The OSS was able to organize a successful guerrilla movement among the Kachin tribesmen of northern Burma, who were hostile to the Burmese and Thai ethnic groups aligned with Japan and against whom the Japanese committed a number of atrocities. These tribesmen were very successful at harassing isolated Japanese outposts, at gathering intelligence, and in serving as guides to regular Allied forces.

In what would eventually become a painful irony, the Communist underground in French Indochina under Ho Chi Minh received encouragement and support from the American 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.

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 much more 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 tribesman alienated by Japanese brutality.

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.

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.

References

Bergerud (1996)

Chang and Holliday (2005)

Dunlop (1979)

Ferguson (1980)

Ramsey and Rivele (1990)