Lord Richard Wellesley served as the Governor-General of Bengal from 1798 to 1805, a period marked by aggressive expansionism and the rapid consolidation of British power in India. Wellesley was a staunch imperialist who aimed to establish British paramountcy over all Indian states, viewing the French threat and the independent Indian powers as obstacles to this goal. His primary instrument for achieving this was the Subsidiary Alliance System, coupled with direct military conquests.

The Subsidiary Alliance System: This system was a shrewd diplomatic and military strategy designed to bring Indian states under British control without direct annexation, at least initially. Its key features were:

1. Acceptance of British Paramountcy: Indian rulers who entered the alliance had to acknowledge the British East India Company as the supreme power in India.
2. Stationing of British Troops: The allied state had to agree to permanently station a contingent of British troops within its territory.
3. Payment for Troops: The state had to either pay for the maintenance of these troops or cede a portion of its territory to the Company for this purpose.
4. Expulsion of Other Europeans: The ruler could not employ any European (especially French) in their service without British permission.
5. British 'Protection' and Non-Interference: The Company promised to protect the allied state from external aggression and internal rebellion, but in return, the ruler had to surrender control over their foreign policy and often faced significant British interference in internal affairs.

Key Expansions and Annexations under Wellesley:

1. Hyderabad (1798): The Nizam of Hyderabad was the first major Indian ruler to accept the Subsidiary Alliance. This brought a significant Deccan state under British influence and secured a strategic ally.

2. Mysore (1799): Wellesley viewed Tipu Sultan of Mysore as a formidable enemy and a potential ally of the French. He launched the Fourth Anglo-Mysore War (1799). Tipu Sultan was defeated and killed at the Battle of Seringapatam. Mysore was then largely dismembered; a small portion was restored to the old Hindu Wodeyar dynasty, who accepted the Subsidiary Alliance, while significant territories were annexed by the British and their allies (Nizam).

3. Awadh (1801): The Nawab of Awadh was compelled to accept the Subsidiary Alliance, ceding half of his territory (including Rohilkhand and the Doab region) to the Company in return for 'protection.' This was a major territorial gain for the British, securing a rich agricultural region.

4. Maratha Confederacy (1802-1805): Wellesley's ambition extended to the powerful Maratha Confederacy. Internal conflicts among Maratha chiefs (Peshwa, Scindia, Holkar, Bhonsle) provided him with an opportunity.

   • Treaty of Bassein (1802): The Peshwa Baji Rao II, defeated by Holkar, sought British protection and signed the Treaty of Bassein, accepting the Subsidiary Alliance. This was a major diplomatic coup, effectively bringing the head of the Maratha Confederacy under British control.
   • Second Anglo-Maratha War (1803-1805): The other Maratha chiefs (Scindia, Bhonsle, Holkar) resisted the Peshwa's submission, leading to war. The British, under Arthur Wellesley (Lord Wellesley's brother) and General Lake, inflicted decisive defeats. Though not fully annexed, the Maratha power was severely crippled, and many Maratha states were forced to accept subsidiary alliances, ceding vast territories.

5. Other States: Wellesley also forced the rulers of Tanjore (1799), Surat (1800), and the Carnatic (1801) to cede their administrations and territories to the Company, often on pretexts of misgovernance or succession disputes.

Impact: Wellesley's aggressive policies dramatically expanded British territorial control and political influence across India. He effectively dismantled the independent power of many Indian states, establishing the Company as the undisputed paramount power. The Subsidiary Alliance, while seemingly offering protection, effectively stripped Indian rulers of their sovereignty, drained their resources, and paved the way for future direct annexations. His tenure laid the groundwork for the complete British domination of the subcontinent.