In 1710, the Gurkhas of Nepal (ruled by Ran Bahadur) invaded Kumaon and occupied Almora. They attacked Garhwal the next year and penetrated as far as Langurgarhi, a strong fortress near the present township of Lansdowne. However, the three year long siege of Langurgarhi had to be lifted when the news of the Chinese invasion of Nepal reached them. All the Gurkha troops were withdrawn. The Raja of Garhwal agreed to pay an annual tribute of twenty five thousand rupees and keep an agent at the court in Kathmandu.

In 1803, a remarkable and highly successful effort was made to conquer Garhwal by the Thapas from Nepal. Ever since the siege of Langurgarhi in 1792, which had to be lifted, small groups or parties of Gurkhas had time and again plundered the border parganas (old districts) of Garhwal. They took hundreds of prisoners in these raids and sold them into slavery. Most villages were burnt and the countryside devastated.

On the other hand, the people of Garhwal, too, made bloody reprisals and there ensued border warfare. These wars were constant deeds of wanton cruelty and ferocious revenge. Many fresh attempts were made to finally capture Langurgarhi.

In 1803, taking advantage of a devastating earthquake that hit Garhwal and Kumaon, that killed almost one third of the population, the Gurkhas assembled a large force under Amar Singh Thapa, Hastidal Chautariya, Bam Sah Chautariya and invaded Garhwal. At that time, Pradhaman Sah was the ruler of Garhwal.

He was very feeble and weak willed. He made no serious attempt to fight
and the major passes were left unguarded. He fled through the Dehradun valley, which was occupied by the invaders in the winter of 1803. Later, the Raja of Garhwal assembled a force at Landhaura near Hardwar and attempted to recover the Dehradun valley. He was killed in action at Khurbura in Dehradun. His son, Sudarshan Sah escaped to British territory and Pritam Sah, the deceased raja's brother was taken to Nepal as prisoner.

Amar Chand Thapa, and his son Ranjor Thapa, began to rule both Garhwal and Kumaon. Preparations were made to expand their conquests towards the west in the year 1804. From the records of the temples and the old revenue records it is evident that Hastidal Sah and Sardar Bhakti Thapa were two able administrators of Garhwal between 1803 and 1815. During the tenure of the former, there was a high level of prosperity in the Dehradun valley. His foreign policy was also vigorous. He speedily put an end to the raids into the Dehradun valley from Punjab and Saharanpur by making a terrible example of a band of marauding Sikhs.

In Garhwal itself, Kazi Amar Singh Thapa was for sometime the governor. Here the principal aim of the Gurkha rule was to extract the maximum amount of tribute or revenue. As a result, he adopted the administrative system of the rajas on which they grafted a military autocracy. Srinagar was the capital and main town of Garhwal. The state was divided into three commands whose headquarters were at Srinagar, Chandpurgarhi and Langurgarhi. Minor civil magistracies were filled by officers having the military title of faujdar.

The government was ruthless but weak. The civil magistrates and officers were corrupt and there was a tendency to keep the fines and revenue collected by them for their personal gain. 'The central administration gave the local officers a free hand and as long as they met the revenue target allotted to them, no questions were asked.

By and large, there was exploitation of the people. 'Their condition became very miserable. Defaulters, who had no means of paying the heavy fines and other demands made by the Gurkhali officials were sold as slaves.

In 1814, Raper (as cited by Walton, 1910) wrote, ''The people are most vehement in their complaints against the Gurkhalis, of whom they stand in the utmost dread, but from the slavish habits and ideas they have contracted, it is doubtful if a spirit of resistance or independence could be excited amongst them. The villagers in Garhwal afford a striking proof of the destruction caused by the Gurkhalis; uncultivated fields, ruined and deserted huts, present themselves in every direction. The temple lands, alone, are well tilled. The Dun was  ruined; under the Gurkhalis, it produced about one-fourth of the revenue realized by the Garhwali Rajas."

It is evident that the Gurkha rule in Garhwal was very harmful, both, for the people and the land. The most negative features of their rule were that the villages were deserted, agriculture was ruined and the population was forced to migrate to the adjoining kingdoms as refugees. Over two lakh people were sold as slaves and taken to Nepal or other kingdoms. Bam Sah and Hastidal, the governors of Garhwal were disposed to indulgence.

The officials were corrupt and treated the people very mercilessly, thus the morale of the people became very low and they were rendered inefficient.