Who introduced the Subsidiary Alliance?

Hint: Subsidiary Alliance along with various other measures, played a crucial role in extending and asserting facets of British paramountcy. The princely states constituted a significant part of British India. The British controlled them but they were not formally annexed.

Complete answer: Lord Wellesley was a colonial administrator and Anglo-Irish politician. He invaded Mysore after a battle and became fifth Governor-general of India.
To expand the political roots and attain more profit in India, Lord Wellesley propagated two methods: outright war and Subsidiary Alliance. This was a major step that led to the strengthening of the British Empire in India. The Subsidiary Alliance, led by the Indian kingdoms lost their sovereignty to the British. This was basically a treaty between the Indian Princely states and the British East India company. The term was introduced by French Governor Dupleix but was put to practice by Lord Wellesley.
Under the alliance, the British would protect the state against any attack or revolt as the Indian ruler would accept British forces in their territory while they dissolve their own forces or army. Under the alliance, the Indian ruler became a British “ protectorate” and lost all their powers in terms of military or political connections.

Note: In 1798, the Nizam of Hyderabad was the first to accept the alliance. Many Indian states lost their independence and wide unemployment took place as they disposed of their armies. Some States under the alliance were Peshwa ( Maratha), Awadh(1801), Mysore (1799).