A medieval western European town which had acquired specific privileges by purchase or force. The privileges might include a charter of liberties, freedom to elect councils, responsibility for regulating local order, justice, and trade, and powers to raise taxes and tolls. The burghers initially swore an oath binding themselves together. The communes often pursued their own diplomatic policies as political alliances shifted. They flourished where central government was weak and became bastions of local power, and after the Reformation, of religious loyalties. The growth of strong national monarchies reduced them in the 16th and 17th centuries.