Simla was founded as a hill station to use as strategic place for billeting troops, guarding frontier and launching campaign during the course of

Simla (Shimla) was founded as a hill station during the course of the Anglo-Gurkha War (1814–1816). The conflict arose from the expansionist policies of the Gurkhas, who had extended their sway from Bhutan to the Sutlej river, leading to border clashes with the British at Gorakhpur. Following the war and the subsequent Treaty of Sagauli in 1816, the British acquired territories in the Himalayas, including Garhwal and Kumaon [1]. Hill stations like Simla were strategically developed for billeting troops, guarding the northern frontiers, and serving as staging grounds for military campaigns [1]. The British recognized the health and strategic benefits of the high-altitude climate for European soldiers, eventually leading to Simla being declared the summer capital of British India in 1864.

Sources

1. [1] Rajiv Ahir. A Brief History of Modern India (2019 ed.). SPECTRUM. > Chapter 5: Expansion and Consolidation of British Power in India > Anglo-Nepalese Relations > p. 126