After India gained independence from the British in 1947, India requested that Portuguese territories on the Indian subcontinent be ceded to India. Portugal refused to negotiate on the sovereignty of its Indian enclaves. On 19 December 1961, the Indian Army began military operations with Operation Vijay resulting in the annexation of Goa, Daman, and Diu into the Indian union. Goa, along with Daman and Diu, was organized as a centrally administered union territory of India. On 30 May 1987, the union territory was split, and Goa was made India’s twenty-fifth state, with Daman and Diu remaining a union territory.

source: http://en.wikipedia.org/wiki/Goa