तस्य सञ्जनयन्हर्षं कुरुवृद्ध: पितामह: |
सिंहनादं विनद्योच्चै: शङ्खं दध्मौ प्रतापवान् || 12||
tasya sañjanayan harṣhaṁ kuru-vṛiddhaḥ pitāmahaḥ
siṁha-nādaṁ vinadyochchaiḥ śhaṅkhaṁ dadhmau pratāpavān
tasya sanjanayan harsham kuru-vriddhah pitamahah
simha-nadam vinadyochchaih shankham dadhmau pratapavan
BG 1.12: Then, the grand old man of the Kuru dynasty, the glorious patriarch Bheeshma, roared like a lion, and blew his conch shell very loudly, giving joy to Duryodhan.
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.