SB 11.1.2
ye kopitah su-bahu pandu-sutah sapatnair
durdyuta-helana-kaca-grahanadibhis tan
krtva nimittam itaretaratah sametan
hatva nrpan niraharat ksiti-bharam isah
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Because the sons of Pandu were enraged by the numerous offenses of their enemies, such as duplicitous gambling, verbal insults, the seizing of Draupadi’s hair, and many other cruel transgressions, the Supreme Lord engaged those Pandavas as the immediate cause to execute His will. On the pretext of the Battle of Kuruksetra, Lord Krsna arranged for all the kings who were burdening the earth to assemble with their armies on opposite sides of the battlefield, and when the Lord killed them through the agency of war, the earth was relieved of its burden.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The Pandavas were repeatedly harassed by their enemies, such as Duryodhana and Duhsasana. As innocent young princes, the Pandavas had no enemy, but Duryodhana was constantly plotting against his helpless cousins. The Pandavas were sent to a house of lac, which was later burned to the ground. They were administered poison, and their chaste wife Draupadi was publicly insulted when her hair was pulled and an attempt was made to strip her naked. Throughout these dangers, Lord Sri Krsna constantly protected the Pandavas, who were fully surrendered to Him and who knew no shelter other than Him.
In this verse the word itaretaratah is significant. Previous to the Battle of Kuruksetra, Krsna had personally killed many demons, including Putana, Kesi, Aghasura and Kamsa. Now, Krsna wanted to complete His mission of removing the earth’s burden by killing the remaining impious persons. But as stated here, krtva nimittam: the Lord did not personally kill, but empowered His devotees Arjuna and the other Pandavas to remove the impious kings. Thus acting personally and through His immediate expansion Balarama, as well as by empowering His pure devotees such as the Pandavas, Krsna fully displayed the pastimes of the yugavatara by reestablishing religious principles and ridding the world of demons. Although the general purpose of the Kuruksetra battle was to kill the demons, by Krsna’s arrangement some great devotees such as Bhisma also appeared to be inimical toward the Lord. But as described in the First Canto of Srimad-Bhagavatam (1.9.39) by the words hata gatah svarupam, many great devotees played with the Lord as enemies and upon being killed by Krsna returned immediately to His abode in the spiritual sky in their original spiritual bodies. Because God is absolute, by His killing He simultaneously removes the demons from the earth and encourages His pure devotees.