After the Pandavas' thirteen year exile was over, they packed up from Virata and headed off to Kurukshetra to wage war against their cousins, finished off the battle in eighteen nights.
Not quite. The path to war was by no means certain, by no means inevitable. It is a tragedy when one reads the several opportunities for peace that went abegging. The story of the terrible eighteen day war often relegates the tale of the Udyoga Parva to a mere footnote. The other story in the Udyoga Parva notable in its own right is that of Amba. In between the several parleys that went on between the Pandavas and Kauravas, there is the staggering Prajagara Parva, where Vidura expounds an entire treatise on statecraft in the middle of the night to Dhritarashtra. It is the presence of such nuggets that make the Mahabharata another reason to read in its entirety.