Since Sri Aurobindo's retiring to Pondicherry in 1910, Amarendra closely associated with Jatin's followers such as Atulkrishna Ghosh, M.N. Roy and Bepin Ganguli, and served as intermediary between Jatin Mukherjee and Rasbehari Bose, becoming a key-figure in the Indo-German Conspiracy under Jatin during World War I. Two of his faithful lieutenants – Basanta and Manmatha Biswas went to North India to assist Rasbehari in an attempt to murder Lord Hardinge; immediately after Basanta's capital punishment in this connection, Amarendra was blacklisted by the Police.