Whenever there is a war, there is certainly a massacre of many innocent living beings, such as boys, brahmanas and women, whose killing is considered to be the greatest of sins. They are all innocent creatures, and in all circumstances killing of them is forbidden in the scriptures. Maharaja Yudhisthira was aware of these mass killings. Similarly, there were friends, parents and preceptors also on both sides, and all of them were killed. It was simply horrible for him to think of such killing, and therefore he was thinking of residing in hell for millions and billions of years.