Due to these political protests, the two parts of Bengal were reunited on 12 December 1911. A new partition which divided the province on linguistic, rather than religious grounds followed, with the Hindi, Oriya and Assamese areas separated to form separate administrative units: Bihar and Orissa Province was created to the west, and Assam Province to the east. The administrative capital of British India was moved from Calcutta to New Delhi as well.
when did the unification of bengal took place
12 December 1911