'Galahad' was a US long-range penetration force operating in northern Burma with the Chinese forces of Lieutenant General Joseph W. Stilwell. The force was more formally known as Unit 'Galahad' or the 5307^th Composite Unit (Provisional), but less formally as 'Merrill’s Marauders' for its first commander, Brigadier General Frank D. Merrill, who had been Stilwell’s chief-of-staff (1943/44).

At the 'Quadrant' or 1^st Quebec Conference of August 1943, Allied leaders decided to form a US deep-penetration unit for attacks on the Japanese in Burma. The new US force was directly inspired by, and indeed partially modelled on Brigadier (later Major General) O. C. Wingate’s British 'Chindit' long-range penetration force, and the initial call for volunteers drew some 3,000 responses. Dated 18 September 1943, a memorandum of the Operations Division of the Department of War listed the proposed structure of this new and all-volunteer US penetration force. Some 960 jungle-trained officers and men came from the Caribbean Defense Command, another 970 jungle-trained officers and men from the Army Ground Forces based in the continental USA, and another 674 battle-tested jungle troops from the South Pacific Command, with all these men to be assembled at Nouméa, the capital of New Caledonia, the largest of the Free French New Hebrides islands group. General Douglas MacArthur was also directed to transfer 274 combat-experienced US Army volunteers (veterans of the New Guinea and Bougainville campaigns) from his South-West Pacific Area command. A few veteran Pacific theatre volunteers came from military prisons, where volunteering earned the men’s freedom: these last were sprinkled throughout the unit.

The men were sent initially for training in India, and arrived in Bombay on 31 October. Here they were reinforced with US Army Air Forces and US Signal Corps personnel, as well as an animal transport company with mules and experienced mule drivers. The mules were used for the movement of radio equipment, ammunition and heavier support weapons, including the bazooka rocket-launcher and 60-mm (2.36-in) mortar: the latter was often used without its baseplate in order to speed deployment.

The 5307^th Composite Unit (Provisional) trained in long-range penetration tactics under the direction of Wingate, and at Deolali, some 125 miles (200 km) from Bombay, the troops endured both physical conditioning and close-order drill, before moving to Deogarh. The unit was to have 700 animals including 360 mules. There were in fact to have been twice as many mules, but the ship carrying them was torpedoed in the Arabian Sea, and these losses led to the adoption of 360 Waler horses from Australia: these had originally been on the strength of the 112^th Cavalry in New Caledonia, but this unit was deemed unfit for jungle warfare, had been transferred to India, where they served with the Chinese army, and were finally assigned to 'Galahad'.

From the end of November 1943 to the end of January 1944, 'Galahad' trained intensively at Deogarh, where all the officers and men received instruction in scouting and patrolling, stream crossing, weapons, navigation, demolition, camouflage, small-unit attack on entrenchments, evacuation of wounded personnel, and the novel technique of supply by airdrop. Special emphasis was placed on 'jungle lane' small arms marksmanship at pop-up and moving targets. In December 'Galahad' undertook a week-long exercise in co-ordination with the 'Chindits'.

However, Lieutenant General Joseph W. Stilwell, the commander of the US/Chinese China-Burma-India theatre, was determined that the only US combat troops in this theatre would not serve under British command. As the only Allied ground commander without infantry of his own army, Stilwell was aware that he would have minimal influence upon Allied ground strategy in Burma unless he could gain command of 'Galahad'. Admiral the Lord Louis Mountbatten, the Allied supreme commander of the South-East Asia command, was persuaded by Stilwell, who was also his deputy, that 'Galahad' should serve under the US/Chinese Northern Combat Area Command. Stilwell appointed Merrill to command 'Galahad', and this inevitably led US war correspondents to nickname the unit 'Merrill’s Marauders'.

Early in 1944, the 'Galahad' force was organised as light infantry assault units, with mule transport, Although the force’s three battalions were each equivalent to a regimental-size unit, its lack of organic heavy weapons support meant the force had a combat power less than that of a single conventional US infantry battalion, which was a fact which Stilwell and his staff did not always remember. Without heavy weapons support, the unit had to rely on flexibility and surprise to outfight considerably larger Japanese forces.

Weight was critical to the unit, and the need for a compact and light field ration was essential. Unfortunately, though, the dry jungle ration, which was the best solution delivering 4,000 calories per day, had been discontinued for cost reasons in 1943. On the advice of US Army supply officers in Washington, Stilwell and his staff decided that a one-per-day issue of the US Army’s 2,830-calorie K ration would be sufficient to maintain men of the unit in the field. While compact, the K ration not only had fewer calories but less bulk, and included some components which were so unappetising that they were almost always thrown away by the men.

On the advice of Wingate, each battalion was divided into two self-contained combat teams. During February 1944, in an offensive designed to disrupt Japanese offensive operations, the six combat teams (coded Red, White, Blue, Khaki, Green, and Orange) of the three battalions marched into Burma. On 24 February, the force began a 1,000-mile (1600-km) march over the Patkai region of the Himalayas and into the Burmese jungle behind the Japanese lines. A total of 2,750 men entered Burma, the remaining 247 remaining in India as headquarters and support personnel.

In Burma, the 5307^th Composite Unit (Provisional) was almost invariably outnumbered by its primary opponent, Lieutenant General Shinichi Tanaka’s 18^th Division of Lieutenant General Masaki Honda’s 33^rd Army, but always inflicted more casualties than it suffered. Led by Kachin scouts, and using mobility and surprise, the unit harassed Japanese lines of communication and supply lines, ambushed patrols, and launched attacks into Japanese rear areas, in one case cutting off the Japanese rearguard at Maingkwan. Near Walawbum, a town believed by the NCAC’s staff to be held only lightly, the 3^rd Battalion killed some 400 to 500 Japanese troops. The Japanese were continually surprised by the heavy, accurate volume of fire they received when they managed to attack the 'Galahad' force’s positions. The combat-experienced US officers had carefully integrated the fire of their light mortars and machine guns, and virtually every man was armed with a self-loading or automatic weapon in which he had trained to a high level of marksmanship. In March the unit severed the Japanese supply lines in the Hukawng valley.

Informed by the British that the situation at Imphal, under siege by the Japanese in 'U' (ii), was under control, Stilwell wanted to launch an assault to capture the Japanese airfield at Myitkyina. Always on his guard as what he saw as possible British interference, Stilwell did not co-ordinate his plans with Mountbatten, but instead sent separate orders to his Chinese forces and to 'Galahad'. The US troops rested briefly at Shikau Gau, a jungle village in which they bartered with the inhabitants for fresh eggs and chickens with an issue of 10-in-1 oil and C rations. The men of 'Galahad' also took the opportunity to sunbathe in an attempt to control the onset of various fungal skin diseases.

Now down to a strength of little over 2,200 officers and men, 'Galahad' began a series of battles on the march to Myitkyina. In April the unit was ordered by Stilwell to take up a blocking position at Nhpum Ga and hold it against Japanese attacks, a conventional defensive action for which the unit was not trained or equipped. At times surrounded, the unit co-ordinated its own battalions in mutual support to break the siege after a series of fierce assaults by Japanese forces. At Nhpum Ga, the unit killed 400 Japanese against the loss of 57 men killed in action, 302 wounded and 379 incapacitated by illness and exhaustion. Of the unit’s 200 mules, 75 had been lost to artillery and mortar fire. A concurrent outbreak of amoebic dysentery further reduced the US unit’s effective strength. Although the unit had previously avoided losses from this deadly disease, in part by the use of halazone chlorine-based water purification tablets and strict field sanitation procedures, its current encampment with Chinese infantry, who used the rivers as latrines, proved disastrous: the Chinese, who always boiled their drinking water, were not seriously affected.

The disadvantages of supplying the men of the US unit with a single K ration per day now made themselves evident, and the men became increasingly malnourished. Moreover, the onset of the rainy season combined with Japanese pressure and terrain factors to prevent many supply drops, which greatly exacerbated the problem. Even now, one K ration (three meals) per day, augmented by occasional drops of dry rice, jam, bread, candy and C rations, was deemed adequate by Stilwell’s staff. When they met Chinese troops, many men began to barter their K ration cigarettes for rice and other foods.

On 17 May, after an exhausting 60-mile (100-km) march over the 6,600-ft (2000-m) Kumon mountain range to Myitkyina, the remaining US soldiers, now numbering about 1,300, and elements of the Chinese 42^nd and 150^th Regiments of 'X' Force, fell on the Japanese holding Myitkyina airfield. The assault was a complete success, but the town of Myitkyina could not be taken with the forces on hand. An initial assault by elements of two Chinese regiments was repulsed with heavy losses. The NCAC intelligence staff had once again badly underestimated Japanese troop strength in the town, which had steadily been reinforced and was now held by a garrison of some 4,600 Japanese troops. Weakened by hunger, 'Galahad' continued fighting through the height of the monsoon season, and it also transpired that the area around Myitkyina had the largest reported incidence of scrub typhus, which some US troops contracted after sleeping on infected areas of untreated earth or grass. Beset by bloody dysentery and fevers, sleeping in the mud, the US troops attacked and defended in a see-saw series of brutal conventional infantry engagements with the Japanese.

After the besiegers had been reinforced by an air-landed Chinese division and and the surviving 'Chindits' of Brigadier J. M. Calvert’s Indian 77^th Brigade, the town finally fell on 3/4 August. The Japanese commander and about 600 men escaped, but 187 others were captured and some 3,800 had been killed in combat.

In its final mission the US unit had lost 272 men killed, 955 wounded, and 980 evacuated for illness and disease. Some of the last later died from cerebral malaria, amoebic dysentery, and/or scrub typhus. Adding insult to injury, the Americans evacuated from the front were given jungle hammocks with protective sandfly netting and rain covers in which to sleep, equipment which might have prevented various diseases and illnesses had they been issued earlier in the campaign.

The casualties included Merrill, who had suffered a second heart attack before going down with malaria. He was replaced by his second in command, Colonel Charles N. Hunter, who later prepared a scathing report on Stilwell’s medical evacuation policies and prompting an investigation by the US Army Inspector General and Congressional hearings.

By the time the town of Myitkyina was taken, only about 200 surviving members of the original 5307^th Composite Unit (Provisional) were still present. A week after the fall of Myitkyina, when the unit was disbanded on 10 August, it had only 130 combat-effective officers and men out of the original 2,997. Of the 2,750 men who had entered Burma, only two were left alive who had nor been hospitalised with wounds or major illness at any time. None of the horses and only 41 mules survived.

In slightly more than five months of combat, the unit had advanced 750 miles (1210 km) through some of the harshest jungle terrain in the world, fought major engagements at Walawbum, Shaduzup, Inkangahtawng, Nhpum Ga and Myitkyina, and engaged in combat with the Japanese on 32 separate occasions, including two conventional defensive battles for which it had not been intended nor equipped. Waging a constant campaign against the Japanese, hunger and disease, the unit had traversed more jungle terrain on its long-range mission than any other US Army formation during World War II.

On 10 August 1944 the surviving men were consolidated into the 475^th Infantry, which continued service in northern Burma as a component of the division-sized 'Mars' Task Force until February 1945.