In September 1939, Bhabha was in India for a brief holiday when World War II started, and he decided not to return to England for the time being. He accepted an offer to serve as the Reader in the Physics Department of the Indian Institute of Science, then headed by renowned physicist C. V. Raman. He received a special research grant from the Sir Dorab Tata Trust, which he used to establish the Cosmic Ray Research Unit at the Institute.