A commandery consisted of a group of counties, and was headed by an Administrator. He was the top civil and military leader of the commandery and handled defense, lawsuits, seasonal instructions to farmers and recommendations of nominees for office sent annually to the capital in a quota system first established by Emperor Wu. The head of a large county of about 10,000 households was called a Prefect, while the heads of smaller counties were called Chiefs, and both could be referred to as Magistrates. A Magistrate maintained law and order in his county, registered the populace for taxation, mobilized commoners for annual corvée duties, repaired schools and supervised public works.