Treaty of Sinchula (1865)

The Treaty of Sinchula (also known as the Ten Article Treaty of Rawa Rani) was a peace agreement signed on 11 November 1865 between the Kingdom of Bhutan and British India, formally ending the Duar War of 1864–1865. The treaty was concluded between His Excellency the Right Honourable Sir John Lawrence, Viceroy and Governor-General of India, represented by Lieutenant Colonel Herbert Bruce, and the Bhutanese representatives Samdojey Deb Jimpey and Themseyrensey Donai. It was the most consequential international agreement in Bhutanese history prior to the twentieth century, permanently reshaping the kingdom’s borders and its relationship with the colonial power to its south.^[1]

Under the treaty’s terms, Bhutan ceded in perpetuity the entire lowland belt known as the Duars — the Assam Duars, Bengal Duars, and the territory of Dewangiri — to British India. This constituted approximately one-fifth of Bhutan’s pre-war domain and included its most fertile and economically productive lands. In return, the British government agreed to pay Bhutan an annual subsidy of 50,000 rupees, conditional upon Bhutanese compliance with the treaty’s terms. The agreement remained the primary framework governing Bhutan’s relations with British India until it was modified by the Treaty of Punakha in 1910.^[2]

Background: The Duar War

Tensions between Bhutan and British India had simmered for decades over control of the Duars — a chain of fertile lowland strips at the foot of the Bhutanese hills stretching across what is now Assam and West Bengal. The Duars were economically valuable for their timber, tea-growing potential, and trade routes connecting the Himalayan interior to the Indian plains. British India had progressively annexed the Assam Duars between 1841 and 1842, paying Bhutan annual compensation, but disputes over the Bengal Duars continued to fester.^[1]

The immediate catalyst for war was the humiliation of the Ashley Eden mission in 1864. The British Indian government dispatched Eden, then Secretary to the Government of Bengal, to Punakha to negotiate the return of captives and establish peaceful relations. When Eden’s mission arrived at the Bhutanese capital, they were subjected to deliberate insult and coercion. Eden was kept standing in the sun, jeered at by crowds, and ultimately forced to sign an agreement on Bhutanese terms in order to secure the safe return of his party. Upon his return, Eden recommended the permanent occupation of the Duars as retaliation.^[3]

On 12 November 1864, British India formally declared war on Bhutan. The British forces, under Brigadier-General Henry Tombs and Brigadier-General David Durand, advanced into the Duars with approximately 5,000 troops. Despite initial Bhutanese resistance — including the dramatic recapture of Dewangiri in January 1865 — the superior firepower and organisation of the British forces proved decisive. By the spring of 1865, Bhutan’s lowland territories were firmly in British hands.^[1]

Key Provisions

Peace and Friendship (Article I)

Article I declared that “there shall henceforth be perpetual peace and friendship between the British Government and the Government of Bhutan.” This article established the formal end of hostilities and set the diplomatic framework for the relationship going forward.

Territorial Cessions (Article II)

The most consequential provision required Bhutan to cede to Great Britain in perpetuity the entirety of the Bengal Duars and Assam Duars, as well as the territory of Dewangiri in southeastern Bhutan and a section of mountainous land on the left bank of the Tista (Teesta) River, later known as the subdivision of Kalimpong. These territories constituted some of Bhutan’s most productive agricultural and commercial lands.^[1]

Return of Captives (Article III)

Article III required the Bhutanese government to surrender all British subjects detained in Bhutan against their will, as well as subjects of the Chiefs of Sikkim and Cooch Behar. This provision addressed one of the longstanding British grievances that had contributed to the outbreak of war.

Annual Subsidy (Article IV)

In return for the ceded territories, Article IV stipulated that the British Government agreed to pay the Government of Bhutan an annual allowance “not exceeding fifty thousand rupees.” Crucially, this subsidy was conditional — the amount could be reduced or withheld entirely if Bhutan failed to comply with the treaty’s terms. This conditionality effectively gave British India financial leverage over Bhutanese affairs for decades.^[4]

Dispute Resolution and Trade

Additional articles established mechanisms for the arbitration of disputes between the two governments and facilitated free trade and commerce between British India and Bhutan. The treaty also provided for the extradition of criminals who had fled across the border.

Consequences for Bhutan

The loss of the Duars was devastating for Bhutan. The lowland territories had been a primary source of revenue, providing agricultural produce, timber, and toll income from trade routes between the hills and the plains. The annual subsidy of 50,000 rupees, while a useful revenue stream, did not come close to compensating for the economic output of the lost territories.^[5]

The treaty also fundamentally altered Bhutan’s strategic position. Confined to the hills, Bhutan lost its direct access to the plains and became more dependent on British India for trade and external engagement. The conditional subsidy payments became a tool of British influence, giving the colonial power an ongoing financial relationship with the Bhutanese state that could be leveraged for diplomatic purposes.

Internally, the war and its aftermath deepened Bhutan’s existing political instability. The ongoing civil wars between regional penlops continued to fracture the country, and the military defeat did little to strengthen the authority of the Druk Desi or the central government. It would take another four decades before Ugyen Wangchuck unified the country and established the hereditary monarchy in 1907.

Legacy

The Treaty of Sinchula remained in force for 45 years until it was modified by the Treaty of Punakha in 1910, which doubled the annual subsidy to 100,000 rupees and formalised British control over Bhutan’s external relations in exchange for a guarantee of Bhutanese internal autonomy. The territorial losses inflicted by the Treaty of Sinchula were permanent — the former Duars remain part of the Indian states of Assam and West Bengal to this day.

The Duar War was the only military conflict between Bhutan and a Western colonial power, and the Treaty of Sinchula its defining outcome. It set the trajectory of Bhutan’s modern foreign policy: a small Himalayan state navigating the interests of larger neighbours through diplomacy rather than force. The treaty also established the pattern of Bhutanese dependence on an annual subsidy from a larger power — a pattern that continued under the 1949 treaty with India and persists in modified form through Indian development assistance to the present day.