History of the Anushilan Samiti
Around 1902, Aurobindo Ghosh arranged for Bannerjee to return to Calcutta to begin organisational work, where he began a gymnasium and a youth society. It was at this time that Bannerjee came in touch with Vibhuti Bhushan Bhattacharya, Sarala Devi Ghoshal and Pramathanath Mitra. In Calcutta, a few clubs and societies were still active at the time. Most notable was a gymnasium in Ballygunge Circular Road run by Sarala Devi herself, a second was an organisation named "Anushilan Samiti" founded by Satish Chandra Basu with the patronage of Pramathanath Mitra. A third one was a youth club called "Attōnnōti Samiti" (Self-improvement society) in central Calcutta.
Anushilan Samiti
The Dhaka Anushilan Samiti embarked on a radical program of political terrorism. It broke with the Jugantar group in West Bengal due to differences with Aurobindo's approach of slowly building a mass base for revolution. The Dhaka group saw this as slow and inadequate, and sought immediate action and results. The two branches of Anushilan engaged in "dacoity" to raise money, and performed a number of political assassinations at this time. In December 1907, the Bengal revolutionary cell derailed a train carrying Bengal Lieutenant Governor Andrew Henderson Leith Fraser in a plot led by the Ghosh brothers. That month, the Dhaka Anushilan Samiti assassinated former Dhaka district magistrate D. C. Allen. The following year, Anushilan engineered eleven assassinations, seven attempted assassinations and explosions and eight "dacoities" in West Bengal. The targets of these actions included British police officials and civil servants, Indian police officers, informants, public prosecutors of political crimes and wealthy families. Under Barin Ghosh's direction, Anushilan members also attempted to assassinate French colonial officials in Chandernagore who were seen as complicit with the Raj.