A self-sufficient prince is one who can meet any enemy on the battlefield. He should be "armed" with his own arms. However, a prince that relies solely on fortifications or on the help of others and stands on the defensive is not self-sufficient. If he cannot raise a formidable army, but must rely on defense, he must fortify his city. A well-fortified city is unlikely to be attacked, and if it is, most armies cannot endure an extended siege. However, during a siege a virtuous prince will keep the morale of his subjects high while removing all dissenters. Thus, as long as the city is properly defended and has enough supplies, a wise prince can withstand any siege.