After fighting with the warriors of Kaurava side, Arjuna issued a divine astra Sanmohana, which stupefied everyone on Kaurava side, except Bhishma.
And with celestial weapons in their hands, they completely surrounded
the son of Pritha and rained on him from all sides a perfect shower of
shafts, like clouds showering on the mountain breast a heavy downpour
of rain, And warding off with weapons, all the weapons of those bulls
among the Kurus, the wielder of the Gandiva who was capable of
enduring all foes, evolved another irresistible weapon obtained from
Indra, called Sanmohana.
And entirely covering the cardinal and other directions with sharp and
keen-edged arrows furnished with beautiful feathers, that mighty hero
stupefied their senses with the twang of the Gandiva. And once more,
taking up with both his hands that large conch of loud blare, Partha,
that slayer of foes, blew it with force and filled the cardinal and
other points, the whole earth, and sky, with that noise. And those
foremost of the Kuru heroes were all deprived of their senses
Arjuna fought with them, just to defeat them and get back the stolen herd of cows. There was no necessity of slaying them. In Mahabharata war, he has to necessarily fight with them and eliminate them for getting victory.