Subsidiary Alliance was a system devised by

The Subsidiary Alliance system was a diplomatic and military strategy devised and formally introduced by Lord Wellesley, who served as the Governor-General of India from 1798 to 1805 [4]. While the concept of using subsidiary forces had roots in the 'Ring Fence' policy of Warren Hastings, Wellesley significantly expanded and formalized it to establish British supremacy and eliminate French influence in India [3]. Under this system, an Indian ruler was compelled to accept a permanent British force within their territory, pay for its maintenance, and station a British Resident at their court [1]. The ruler also had to surrender their foreign relations and could not employ other Europeans without British consent [3]. The first major state to accept this alliance was Hyderabad in 1798, followed by others like Awadh and the Marathas [2].

Sources

1. [1] Rajiv Ahir. A Brief History of Modern India (2019 ed.). SPECTRUM. > Chapter 5: Expansion and Consolidation of British Power in India > Subsidiary Alliance > p. 120
2. [4] http://indianculture.gov.in/digital-district-repository/district-repository/awadh-and-subsidiary-alliance-wellesley-and
3. [2] Rajiv Ahir. A Brief History of Modern India (2019 ed.). SPECTRUM. > Chapter 34: The Indian States > II. Policy of Ring Fence (1765-1813) > p. 604
4. [3] Rajiv Ahir. A Brief History of Modern India (2019 ed.). SPECTRUM. > Chapter 5: Expansion and Consolidation of British Power in India > Subsidiary Alliance > p. 121