The Penlop of Paro, unlike Trongsa, was an office appointed by the Druk Desi's central government. Because western regions controlled by the Penlop of Paro contained lucrative trade routes, it became the object of competition among aristocratic families. Although Bhutan generally enjoyed favorable relations with both Tibet and British India through the 19th century, extension of British power at Bhutan's borders as well as Tibetan incursions in British Sikkim defined politically opposed pro-Tibet and pro-Britain forces. This period of intense rivalry between and within western and central Bhutan, coupled with external forces from Tibet and especially the British Empire, provided the conditions for the ascendancy of the Penlop of Trongsa. After the Duar War with Britain (1864–65) as well as substantial territorial losses (Cooch Behar 1835; Assam Duars 1841), armed conflict turned inward. In 1870, amid the continuing civil wars, the 10th Trongsa Penlop Jigme Namgyal ascended to the office of Druk Desi. In 1879, he appointed his 17-year-old son Ugyen Wangchuck as Penlop of Paro. Jigme Namgyal reigned through his death 1881, punctuated by periods of retirement during which he retained effective control of the country. The pro-Britain 12th Trongsa Penlop Ugyen Wangchuck ultimately prevailed against the pro-Tibet and anti-Britain Penlop of Paro after a series of civil wars and rebellions between 1882 and 1885. After his father's death in 1881, Ugyen Wangchuck entered a feud over the post of Penlop of Trongsa. In 1882, at the age of 20, he marched on Bumthang and Trongsa, winning the post of Penlop of Trongsa in addition to Paro. In 1885, Ugyen Wangchuck intervened in a conflict between the Dzongpens of Punakha and Thimphu, sacking both sides and seizing Simtokha Dzong. From this time forward, the office of Desi became purely ceremonial.