Bheeshma was aware that Duryodhana had no chance of victory as the Supreme Lord Shree Krishna was on the opposite side. However, he understood his grand-nephew’s anxiety and to cheer him up he blew his conch shell loudly. In olden days, blowing of the conch shell in the battlefield signaled the start of the war. This also conveyed to Duryodhana that Bheeshma was ready to lead the Kaurava army and he would fight dutifully and spare no pain.