Daśame’hani Bhīṣma-yuddham — Śikhaṇḍī-rakṣaṇa, Arjuna-prabhāva, Duryodhana-āśraya-vākyam
ततो दुर्योधनो राजा सुशर्माणमचोदयत्् | द्रोणस्य समरे राजन् पार्ष्णिग्रहणकारणात्,राजन! तब राजा दुर्योधनने सुशर्माको समरभूमिमें द्रोणाचार्यके पृष्ठभागकी रक्षाके लिये प्रेरित किया
tato duryodhano rājā suśarmāṇam acodayat | droṇasya samare rājan pārṣṇigrahaṇa-kāraṇāt ||
Sañjaya said: Then King Duryodhana urged Suśarmā to act, instructing him—O King—to serve in battle as the rear-guard for Droṇa, so that Droṇa might not be seized from behind.
संजय उवाच
Even amid war, responsibility toward one’s commander and the integrity of formation matter: safeguarding a leader from a rear seizure is presented as a necessary duty within kṣatriya conduct and battlefield order.
Duryodhana directs Suśarmā to take up a protective role in the battle specifically to guard Droṇa’s rear, preventing enemies from capturing or striking Droṇa from behind.