The Milk Wars was a war between Kulas of Conk and the Weasel King (presumed to be Professor Von Kriplespac). The backstory was told by Conker's ancestor, Count Batula in the Spooky chapter of Conker's Bad Fur Day and Conker: Live & Reloaded. It was also told in Panther King's description of the Bad Fur Day manual. The manual states that the events may not have happened.
In the Heist chapter, Conker finds out that the Panther King is real. Conker previously thought that the Panther King was only a character in bedtime stories his mother used to read to him. He obviously referred to the Milk Wars.
Little is known about the Milk Wars. It was originally fought between the Kulas of Conk and the Weasel King. As the Panther King rose to power, he cut off the Weasel King's legs. He then betrayed his former allies, the Kulas of Conk, in a surprise invasion and overtook the kingdom, which was renamed to "Panther Kingdom". The Panther King betrayed the Kulas of Conk and sent them to "The Dark Place".