Born April 3 in Nasbyhoved, near Odense, in 1878, Jensen was seconded from the Danish army to the Siamese Provincial Gendarmerie in 1900 at the rank of Captain in order to maintain peace and control in Northern Siam's (now Thailand) rural and sparsely populated areas. It was there, only two years later, he became involved in the suppression of the infamous 'Shan Rebellion' of 1902.
The Shan dacoits were Burmese and, as such, were British citizens, many thousands of whom had been employed it the teak cutting and ruby mining industries of Northern Siam. After many years of corruption and harsh treatment by their Siamese overlords in Bangkok they were simmering with anger and ripe for rebellion. They were harassed and overly taxed on such items as tobacco, pack animals, boats and even their own pigs. The final straw had been when a four-rupee poll tax that was meant to replace a forced labour tax but didn't, was enforced.
Because of the obvious stirrings, a company of Gendarmerie was dispatched to the area but the dacoits were forewarned. On the night of July 23, 1902 they ambushed the party while sleeping, killing a number with the remainder fleeing for their lives.
Realizing there was no turning back they finally rebelled fully and attacked the nearby township of Phrae, sacking the town and killing many locals, including the Governor, whom they beheaded. The rebellion had begun.
There is a serious school of thought that holds that the rebellion was inspired by the British in Burma in an effort to control this valuable area of Northern Thailand, although there is no documented evidence to support this theory, which is hardly surprising. This, of course, does not mean it is untrue and many questions have been raised about the British involvement. For example, for such a comparatively small band of rebels (approximately 300) they obviously had to be well armed and provisioned to be able to cover the distances they did.
Also, it is worth noting that this area of Northern Siam, including the capital of Chiang Mai, was held by the Burmese in the middle of the 19th Century and was still considered Burmese territory by them.
From Phrae, where the rebellion began, to Lampang is a distance of approximately 200 kilometres; so it is difficult to imagine a group of poverty-stricken peasants achieving this without assistance.
Although there were no more than 300 rebels they were obviously a determined, fierce, and well organized force for they then marched south to attack the City of Lampang, 100 kilometres south from Chiang Mai.
Captain Jensen, who was placed in charge of the defence of Lampang, arrived from Chiang Mai on July 29 with a lieutenant and 54 soldiers and had the town barricaded to fend off the attackers.
He was joined shortly after by his Second-in-Command, Louis T. Leonowens who was an officer in the Royal Siamese Cavalry and, jointly, they organized the defence of the city and arranged the evacuation of the women and children.
Together, Captain Jensen and Leonowens successfully fought the rebels off and both men were reported to have acted with considerable bravery.
Leonowens himself was a colourful character and was the son of Anna Leonowens of 'The King and I' fame. He had business interests in the teak industry and was a founding member, in 1898, of the Gymkhana Club in Chiang Mai, the first of its kind in Siam and still in existence. (It is of interest to note that Leonowens had a cousin named William Pratt who went to Hollywood, changed his name, and became Boris Karloff.)
The British Consul in the northern capital, W. R. D. Beckett, was severely criticized by Leonowens for his role in the uprising, as he chose to remain in Chiang Mai and fortify that city. He thought the consul should have gone to meet and negotiate with the dacoits as they were British citizens. Instead, he sent his deputy.
Having defeated the rebels at Lampang, killing 52 of them, Captain Jensen decided to pursue the remainder and finally put an end to their murderous rebellion. He chased them all the way to the city of Phayao (pronounced Pie-yow) with a force of 270 men. Eventually, he caught up with a group of rebels and opened fire. The fire was returned and Markvard Jensen was struck in the chest three times and killed.
His body was recovered the following day by another Danish officer, Captain Halfdan Trolle, and taken back to Lampang where it was buried with full military honours. Shortly after the Second World War the cemetery in Lampang was closed and Jensen's body was removed to its present resting place in Chiang Mai.
For his actions in suppressing the uprising in Lampang King Chulalongkorn immediately promoted him to Major and awarded him 10,000 baht, a fortune in those far off days.
Unfortunately, Jensen never lived to see either promotion or reward.
In recognition of his gallantry the King then awarded his mother a monthly pension of 3,000 baht for the rest of her life; which she received until her death in 1936.
Chiang Mai (Northern Thailand) Tourist Guide