Narendranath Bhattacharya, later known as M. N. Roy, was in his youth a devoted revolutionary and lieutenant to a famous Bengali revolutionary leader, Jatin Mukherjee. A description of the revolutionary career of Roy is useful and appropriate for several reasons. First, Roy is one of the few revolutionary Bengalis about whom interesting data is available. Second, Roy followed a pattern oft-repeated among Bengali political workers during the twentieth century: from terrorist and insurrectionary activity to Communism and then open Congress work. Third, both the data collected about Roy and some of his own writings give graphic pictures of two important features of Bengali revolutionary politics: the dal or faction and the dādā or leader of such a group.