The Bank of Calcutta was founded on June 2, 1806, mainly to fund General Wellesley

Richard Wellesley, 1st Marquess Wellesley

Richard Colley Wesley, later Wellesley, 1st Marquess Wellesley, KG, PC, PC , styled Viscount Wellesley from birth until 1781, was an Anglo-Irish politician and colonial administrator....

's wars against Tipu Sultan

Tipu Sultan

Tipu Sultan , also known as the Tiger of Mysore, was the de facto ruler of the Kingdom of Mysore. He was the son of Hyder Ali, at that time an officer in the Mysorean army, and his second wife, Fatima or Fakhr-un-Nissa...

 and the Maratha

Maratha

The Maratha are an Indian caste, predominantly in the state of Maharashtra. The term Marāthā has three related usages: within the Marathi speaking region it describes the dominant Maratha caste; outside Maharashtra it can refer to the entire regional population of Marathi-speaking people;...

s. It was renamed Bank of Bengal on January 2, 1809.

The Bank of Calcutta, and two other Presidency banks, namely, the Bank of Bombay

Bank of Bombay

Bank of Bombay was the second of the three presidency banks of the Raj period. It was established, pursuant to a charter of the British East India Company, in the year 1868, about a decade after India's First War of Independence. The bank was headquartered in Bombay, now called Mumbai...

 and the Bank of Madras

Bank of Madras

The Bank of Madras, one of the three Presidency Banks, the other two being, the Bank of Bengal and the Bank of Bombay, was established on 1 July 1843, and was headquartered in Madras, now Chennai. It is now subsumed in the State Bank of India.-Origin:...

 were amalgamated and the reorganized banking entity was named the Imperial Bank of India

Imperial Bank of India

The Imperial Bank of India was the oldest and the largest commercial bank of the Indian subcontinent, and was subsequently transformed into State Bank of India in 1955.-Origin:...

 on 27 January 1921. The Reserve Bank of India

Reserve Bank of India

The Reserve Bank of India is the central banking institution of India and controls the monetary policy of the rupee as well as US$300.21 billion of currency reserves. The institution was established on 1 April 1935 during the British Raj in accordance with the provisions of the Reserve Bank of...

, which is the central banking organization of India, in the year 1955, acquired a controlling interest in the Imperial Bank of India and the Imperial Bank of India was christened on 30 April 1955 as the State Bank of India.

Further reading

• THE EVOLUTION OF THE STATE BANK OF INDIA, Volume 1 — The Roots 1806-1876 by Amiya Kumar Bagchi http://www.hindu.com/br/2007/04/03/stories/2007040300301600.htm