Major Dhan Singh Thapa was born on April 10 1928 in Shimla, Himachal Pradesh. On 28 August 1949 he was commissioned into the 8th Gurkha Rifles.

During the Sino-Indian was Thapa was involved in a major military action in the ladakh .

The Sirijap valley which is on the north of Pangong Lake in Ladakh, was considered curtail for the protection of Chushul airfield. The 1/8 G.R had outposts in that area to counter any encroachment attempt from the Chinese side. on 20 October 1962 the Chinese attacked One such outposts named Sirijap-1 was held by a platoon of C Company, which was commanded by Major Thapa.

on 20 October 1962 at around 06:00 am the Chinese forces opened heavy  artillery and mortar fire on the Sirijap-1 post. This heavy shelling continued till 08:30 am and the whole area was set ablaze.  Shells also fell on the command post and which completely damaged the wireless set and put the post out of communication from the base.  Chinese forces then attacked with  overwhelming strength.  Major Thapa and his troops countered the attack very bravely but they had to take heavy causalities. The Chinese troops  attacked again with much greater strength after shelling the area with mortar and artillery  fire.

Major Thapa defeated them once again causing heavy losses on the Chinese side.

After a short while ,  Chinese troops launched a third attack. It included tanks in support of the infantry. Thapa's troops were weakened from the heavy casualties sustained in the last two attacks but they held on till their ammunition lasted. Even when the post was finally overrun  Major Thapa came out of the trench and killed many enemy soldiers in hand to hand combat. Eventually he was over powered and captured by Chinese troops.

Major Dhan Singh Thapa was honored with the highest wartime gallantry medal, the Param Vir Chakra For his gallant act. He was believed to have been killed in this operation. The original citation reflected this. It was later found out that he has been taken prisoner and held in a POW camp. After the release MAJOR DHAN SINGH THAPA resumed his active duty and retired as Lieutenant Colonel.