Karen fought courageously behind Japanese lines with Seagrim, a lanky, eccentric and exceptional guerrilla leader. But for this ethnic group, Japan’s surrender on Aug. 15, 1945, did not usher in parades and happy homecomings. Instead, victory precipitated the world’s longest running insurgency, a brutal conflict for self-determination that has yet to be resolved.

Some wonder if history might have been different for the Karen if Seagrim had survived the war.

“I think he could have been a good moderating influence at the time of the civil war between the Karen and government,” said Philip Davies, British author of an upcoming book — “England’s Lost Warriors — Seagrim and Pagani of Burma.”

“Suppose he (Seagrim) was still living, he would be helping to support the Karen. Definitely,” said 92-year-old Saw Berny, a veteran who fought with Seagrim and witnessed his surrender to the Japanese.

“We have never stopped praying for him because he loved our people.”

Berny, a Christian like many Karen, and some 20 of his former comrades-at-arms will hold a simple ceremony on Saturday, Victory over Japan Day, at the communal grave in Yangon where Seagrim’s body lies.

Also taking part will be Sally McLean, a British humanitarian aid worker who in 1998 met an old, destitute Karen along the Thai-Myanmar border who had fought with the British. He and his comrades were not recognized as being officially part of the British army and therefore never received pensions or other benefits. So she started Help 4 Forgotten Allies, which provides £120 ($187) each year to more than 250 veterans or their widows.

Some of her donors are also still angry that during the war Britain promised to back the Karen quest for greater autonomy, but on granting the country independence in 1948 did virtually nothing to help a people who often referred to the British as “father.”

The Karen rose up against the central government of what was then Burma in early 1949, the first of numerous ethnic minority insurgencies plaguing the country’s modern history and marked by killings, torture and rape of civilians by Myanmar’s military. Aid agencies say some 400,000 Karen have been driven from their homes while more than 120,000 refugees, most of them Karen, are sheltered in camps along the Thai-Myanmar border. About 60,000 now live in the United States.

A cease-fire was declared in 2012 but fighting continues to erupt and a peace agreement is still in question.

Seagrim was the son of an Anglican clergyman; all four of his brothers also served in the military. A 1947 book, “Grandfather Longlegs” by Ian Morrison, describes him as “an eccentric, a bit of a fanatic, a clever and delightful person, but rather an odd one.”

During his time in Yangon before the war, he shunned colonial society and its snobbery, preferring to trek into remote areas with Karen friends. Rather than a regimental, spit-and-polish officer, he gravitated to the role of a maverick guerrilla chief.

When the Japanese bombed Yangon on Christmas Eve 1941 as a prelude to invasion, Seagrim volunteered to trek into the hills of eastern Myanmar to raise a Karen force. Within two weeks, he mustered 3,000 recruits who soon found themselves deep behind Japanese lines as the defeated British retreated to India. At home in their rugged terrain, the guerrillas attacked supply routes, set lethal ambushes and radioed valuable intelligence about Japanese activities.

Sharing their dangers and threadbare existence, Seagrim drew closer to the Karen, calling them “God’s chosen people” and talking about remaining among them after the war. They called him “Grandfather Longlegs” for his 6-foot, 4-inch frame and being older than most of his comrades-in-arms.

David Eubank, an American who has spent years aiding the Karen, believes Seagrim continues to inspire. “He gave his life for their freedom. This was not only freedom from Japan’s rule but freedom from all tyranny, which now includes that of the dictators in suits,” he said, referring to Myanmar’s current military-backed regime.

“It is extraordinary that 70 years later he is still so revered,” said Davies, the author. “He was so unlike any British officer of the period. He lived with the Karen, helped till their fields, shared his food with them. He regarded them as equals. I think this had a huge impact on the Karen.”

Seagrim’s latent religious faith emerged with intensity behind enemy lines. Roy Pagani, a British soldier who met Seagrim while escaping from the Japanese, described him as long-haired, looking like an Asian and carrying “his tommy gun in one hand with a Bible under the other arm.”

From his youth, Seagrim had been “groping for the meaning of life, and this became more and more powerful when he was isolated behind Japanese lines,” Davies said.

One of Seagrim’s Karen companions, Ta Roe, remembered him saying, “Christ sacrificed for the world. I will sacrifice for the Karen.” And he did.

Seagrim’s fighters proved so effective that the Japanese mounted a tobatsu, a punitive expedition into the Karen hills, torturing and killing villagers in trying to extract information about the major’s whereabouts. A number died rather than reveal his location.

According to Morrison’s book and other accounts, the Japanese then threatened nearly 300 Karen with retribution if Seagrim didn’t surrender. They promised he would be treated like a prisoner of war and not face execution.

The Karen urged him to flee. Instead, Seagrim walked into a Japanese camp and handed his pistol to a Japanese captain.

Wracked by diseases during an agonizing imprisonment, other Allied prisoners later testified to Seagrim’s unfailing good humor and solicitous care for fellow captives. He reportedly refused to bow to the Japanese but said he forgave them, and gained their respect. One Japanese officer described him as “a gentleman, a man of high character.”

Emaciated, shaggy-bearded and wearing Karen dress, Seagrim and 17 Karen faced a Japanese military tribunal that summarily sentenced him and seven of his companions to death.

“He pleaded that the others were following his orders and as such should be spared, but they were determined to die with him,” reads the citation of the George Cross, awarded posthumously for his “conspicuous gallantry.”

On a September day in 1944, the eight condemned were driven to the execution ground of the Kemmendine cemetery. Ta Roe, one of the last witnesses to see him, remembered Seagrim was “smiley-faced” as he boarded a truck and shouted “Good-bye to you all.”

Shortly thereafter, Seagrim, aged 35, was cut down by a firing squad.

Marking his grave today is a simple headstone without a real epithet.

But in 1985, a group of Karen provided their own. They traveled 5,000 miles from Myanmar to place a plaque in Seagrim’s native village of Whissonsett in eastern England. It reads: “Grandfather Longlegs. We remember. So we came. We thank you.”

*This article first appeared on Washington Post on August 15, 2015.