In September 1961, the Gorkha Rifles was a part of the UN's Operation in stife torn Congo. Along with an Irish company it advanced along Lufira bridge to relieve UN forces besieged by the enemy at Jadotville.

The enemy was strongly entrenched in the area and the UN forces were soon compelled to retreat. They had retreated a few kilometers when they were caught in an ambush. Though grievously injured. Thapa held on till the last of the retreating forces and reached a safe position.

He succumbed to his injuries soon afterwards. Naik Mahabir Thapa was posthumously honoured with the Mahavir Chakra for the courage of highest order.