The only trait which Greenskins respect when it comes to leadership is strength. As Greenskins grow older, they grow in stature, becoming tougher and stronger. The biggest and most powerful Orcs are able to challenge for leadership of the tribe to become the Warboss, which they can only do by fighting and beating the existing Warboss. Their love of fighting means that Greenskin tribes are frequently fighting other tribes, since they�re usually the nearest opponents capable of putting up a decent fight. Occasionally, a tribe will recognize the obvious superiority of a rival Warboss, and the two tribes will join together to form an even stronger tribe. If an especially strong Warboss appears, his tribe can quickly become the dominant force in the area, as all the smaller local tribes are compelled to submit to his leadership, forming into one massive rampaging horde. This is known as the Waaagh!