Jolly Roger Historically,
the flag was flown to frighten pirates' victims
into surrendering without a fight,
since it conveyed the message that the attackers were outlaws
who would not consider
themselves bound by the usual rules of engagement.
Since the decline of piracy, various military units have used the Jolly Roger, usually in skull-and-crossbones design,
as a unit identification insignia or a victory flag to ascribe to themselves the proverbial ferocity and toughness of pirates.