So Duryodhana was doubting that "My grandfather, Bhīṣma, is more affectionately inclined to the other party. So he may not be lenient in fighting." So in order to encourage Duryodhana, tasya sañjanayan harṣam. "Don't think that I am lenient. I am strong." Immediately, to encourage him, he blew his conchshell. Nowadays they use bugle. Formerly the conchshells were used by the kings.