William the Conqueror is a volume in the Just William series where William Brown is likely given the title due to a particularly successful, or perhaps particularly chaotic, feat of dominance. The stories in this collection focus on William's attempts to assert his will over his friends, his family, or his immediate environment. Whether he is trying to stage a successful invasion of an enemy territory (a local field) or force his family to adhere to his absurd rules, William sees himself as a historical figure, a ruthless and magnificent leader. The book humorously details how William's attempts at "conquering" usually end with him in trouble or thoroughly defeated by the realities of the adult world.