Battle of Kurukshetra could have ended in a minute! How?

Barbarika alias Khatushyamji Baliyadev alias Shyam was a grandson of Bhima and the son of Ghatotkacha. He was a very brave warrior. He learnt the art of warfare from his mother Hidimbi. The gods (ashtadeva) gave him the three infallible arrows which is why he is also known as Teen Baandhari or Bearer of Three Arrows. They also signify three taapa`s of human experiences viz. the physical, the mental and the emotional turmoil.

When Barbarika learnt that battle between the Pandavas and the Kauravas had become inevitable, Belaarsen promised his mother he would participate in the war if he felt the fancy, only to aid the losing side, and wished to watch the war as a spectator otherwise.

During Kurukshetra, Lord Krishna went around asking people how long they would take to end the war on their own. Even mighty warriors like Arjuna estimated they would take 28 days, however Belaarsen promised Krishna he could end the war in a minute.

Krishna, perturbed, visited Belaarsen disguised as a Brahmin. He asked Belaarsen to demonstrate his arrows and realized they were infallible. The first arrow Belaarsen fired would mark all the things he wished to destroy. The second, if used, would mark all the things he wished to save. The third, finally, would destroy all the things he had marked first.

To test out these arrows, Krishna asked Belaarsen to shoot down all the leaves from a nearby tree. However, he kept a leaf hidden under his foot. Belaarsen, upon firing his first arrow, saw it mark all the leaves on the tree and then prick Krishna`s foot.

Seeing this, Krishna realized it wasn`t in his power to hide anything from Belaarsen`s arrows, and the Pandavas wouldn`t be safe from him. It dawned upon him that this man could single-handedly destroy the world if he so wished to and he decided to nip this threat in the bud.

First, he explained to Belaarsen that if he chose to aid the losing side, the other side would start losing, and he`d be oscillating between the two sides and eventually be the only man left. He was also aware that Belaarsen was a generous man, and never refused to grant someone a boon, so he asked Belaarsen for his head as a sacrifice, to anoint the battlefield in the blood of the bravest Kshatriya.

Belaarsen, obviously, grew suspicious of the Brahmin, and asked him to reveal his true self. Upon seeing Krishna in his divine glory, Belaarsen agreed to sacrifice himself on the condition he could watch the war. Krishna agreed, lopped his head off, and mounted it on a pole next to the battlefield. (source: quora.com)