It was due to Lord Krsna's grace that Arjuna alone, sitting on the chariot, could manage to vanquish them one after another without difficulty

Expressions researched:
"it was due to Lord Kṛṣṇa's grace that Arjuna alone, sitting on the chariot, could manage to vanquish them one after another without difficulty"

Srimad-Bhagavatam

SB Canto 1

On the Kaurava side there were many stalwart commanders like Bhīṣma, Droṇa, Kṛpa and Karṇa, and their military strength was as insurmountable as the great ocean. And yet it was due to Lord Kṛṣṇa's grace that Arjuna alone, sitting on the chariot, could manage to vanquish them one after another without difficulty.

SB 1.15.14, Translation and Purport

The military strength of the Kauravas was like an ocean in which there dwelled many invincible existences, and thus it was insurmountable. But because of His friendship, I, seated on the chariot, was able to cross over it. And only by His grace was I able to regain the cows and also collect by force many helmets of the kings which were bedecked with jewels that were sources of all brilliance.

On the Kaurava side there were many stalwart commanders like Bhīṣma, Droṇa, Kṛpa and Karṇa, and their military strength was as insurmountable as the great ocean. And yet it was due to Lord Kṛṣṇa's grace that Arjuna alone, sitting on the chariot, could manage to vanquish them one after another without difficulty. There were many changes of commanders on the other side, but on the Pāṇḍavas' side Arjuna alone on the chariot driven by Lord Kṛṣṇa could manage the whole responsibility of the great war. Similarly, when the Pāṇḍavas were living at the palace of Virāṭa incognito, the Kauravas picked a quarrel with King Virāṭa and decided to take away his large number of cows. While they were taking away the cows, Arjuna fought with them incognito and was able to regain the cows along with some booty taken by force—the jewels set on the turbans of the royal order. Arjuna remembered that all this was possible by the grace of the Lord.