BG Chap 11 - Arjuna's pitiful state

Arjuna was also filled with terror and said seeing the Lord touch the heavens, shining in many colors, with gaping mouth, and wide, blazing eyes, he was distressed in mind, and did not find any satisfaction or relief. The form touched the sky, spread into the space between earth and heaven, and had a gaping mouth. Here Arjuna expressed his rasa of fear. Seeing the form’s mouths with sharp teeth, like the fire of cosmic destruction, Arjuna could not recognize the directions and felt no comfort. He asked the Lord to be merciful unto him.

Arjuna saw all the sons of Dhṛtarāṣṭra like Duryodhana and others, along with their allied kings such as Śalya and Jayadratha, and also Bhīṣma, Droṇa and Karṇa enter into the fearful mouths of the terrible form. Arjuna also saw the chief warriors from his side such as Dhṛṣṭadyumna entering the mouths. Some of those entering the mouths were seen to be stuck between the teeth with their heads crushed. Some entered the mouths unintentionally like the many swift currents of rivers flowing towards the sea, and some entered knowingly like the moths entering a blazing fire to meet their destruction. Arjuna saw that the form was swallowing all these men and licking the lips repeatedly. The fierce rays filling the whole universe with their splendor were burning it up. The form of Viṣṇu was spread throughout the universe and thus it was impossible to flee from Him.

The Lord said He is Time, the great destroyer of the worlds. His mission was to destroy all people. With the exception of the Pāṇḍavas, all the soldiers on both sides of the army would be slain. The Lord also implied that even without Arjuna fighting, all the warriors would be killed. In the form of time, Kṛṣṇa would take away their lifespan. But if Arjuna did not fight, he would have deviated from his dharma.