The Constituent Assembly, headed by the prominent lawyer, reformer and Dalit leader, B.R. Ambedkar was tasked with creating the constitution of free India. The Constituent Assembly completed the work of drafting the constitution on 26 November 1949; on 26 January 1950, the Republic of India was officially proclaimed. The Constituent Assembly elected Rajendra Prasad was the first President of India, taking over from Governor General Rajgopalachari. Subsequently, the French ceded Chandernagore in 1951, and Pondichéry and its remaining Indian colonies by 1954. Indian troops invaded and annexed Goa and Portugal's other Indian enclaves in 1961, and Sikkim voted to join the Indian Union in 1975 after the Indian victory over China in Nathu La and Cho La.