The Anglo-Nepalese War (1 November 1814 – 4 March 1816), also known as the Gorkha War, was fought between the British East India Company and the Kingdom of Nepal. The conflict was caused by territorial disputes and expansionist ambitions on both sides. Nepal had expanded westward and eastward in the late 18th century, bringing it into conflict with British interests in northern India.

Fighting took place across rugged Himalayan terrain, with the British facing strong resistance from Nepalese forces under commanders such as Amar Singh Thapa. Early British setbacks were followed by advances under leaders like Sir David Ochterlony. The war ended with the Treaty of Sugauli in 1816, through which Nepal ceded significant territory to the Company. The performance of Nepalese troops during the war led to the later recruitment of Gurkhas into the British army.

In the mid-eighteenth century, the British East India Company actively traded with Nepal. Viewed as an opulence hub, Nepal supplied the Company with commodities such as rice, butter, oil seeds, timber, dyes, and gold. In 1767, British concerns around this partnership grew when the Gorkhas ascended their power and leadership in Nepal. In 1768, the Gorkhas conquered Kathmandu Valley and became Nepal’s ruling force, paving the way for a declining relationship between British India and Nepal. In 1801, the Company established a British Residency in Kathmandu to seek a stronger hold over the region. As 1814 approached, however, the British found themselves concerned by the possibility of an alliance between Nepal and Sikhs in northern India. The Company believed that if Nepal was expelled from its Western lands, the “Terai” region, it would no longer pose a danger. In 1814, this is what the British set out to do, alongside a goal of establishing a second Residency in Kathmandu to keep a close watch on the nation. In May 1814, British forces in Nepal temporarily left to escape malaria season. When Nepali forces aimed to reassert power, Company officials were killed in the process. In 1814, Warren Hastings – Governor General of Bengal – officially declared war on Nepal. 16,000 troops were then sent to invade Nepal in September 1814. The Treaty of Sagauli (1816) then marked the end of the Anglo-Nepalese War.

The Shah era of Nepal began with the Gorkha King Prithvi Narayan Shah invading Kathmandu Valley, which consisted of the capital of the Malla confederacy. Until then, only the Kathmandu Valley had been referred to as Nepal. The confederacy requested help from the East India Company, and an ill-equipped and ill-prepared expedition, numbering 2,500, was led by Captain Kinlock in 1767. The expedition was a disaster, and the Gorkhali army easily overpowered those who had not succumbed to malaria or desperation. The ineffectual British force provided the Gorkhali with firearms and filled the Gorkhas with confidence, which possibly caused them to underestimate their opponents in future wars.

Victory and the occupation of the Kathmandu Valley by Prithvi Narayan Shah, starting with the Battle of Kirtipur, resulted in the shift of the capital of his kingdom from Gorkha to Kathmandu, and the empire that he and his descendants built then came to be known as Nepal. Also, the invasion of the wealthy Kathmandu Valley provided the Gorkha army with economic support for furthering their martial ambitions throughout the region.

To the north, however, aggressive raids into Tibet over a long-standing dispute over trade and control of the mountain passes triggered Chinese intervention. In 1792, the Chinese Qianlong Emperor sent an army that expelled the Nepalese from Tibet to within 5 kilometres (3.1 mi) of their capital, Kathmandu. Acting Regent Bahadur Shah (Prithvi Naryan's younger son) appealed to the British Governor-General of India for help. Anxious to avoid a confrontation with the Chinese, the Governor-General did not send troops but sent Captain Kirkpatrick as mediator. However, before he arrived the war with China had finished.

The Tibet affair had postponed a planned attack on the Garhwal Kingdom, but by 1803, the Raja of Garhwal, Pradyuman Shah, had also been defeated. He was killed in the struggle in January 1804, and all his land was annexed. Further west, general Amar Singh Thapa overran lands as far as Kangra, Himachal Pradesh, the strongest fort in the hill region, and laid siege to it. However, Maharaja Ranjit Singh, the ruler of the Sikh state in Punjab, intervened and had driven the Nepalese army east of the Sutlej River by 1809.

In the years leading up to the war, the British had been expanding their sphere of influence. While the Nepalese had been expanding their empire – into Sikkim to the east, the Kumaon and the Garhwal to the west, and into Awadh to the south – the British East India Company had consolidated its position in India from its main bases of Calcutta, Madras and Bombay. This British expansion had already been resisted in India, culminating in three Anglo-Maratha wars as well as in the Punjab where Ranjit Singh and the Sikh Empire had their own aspirations.^{[citation needed]}