Recruits must be Catholic males between 19 and 30 who have completed their mandatory Swiss military service; they sign up for a minimum of two years. The force at the moment numbers 110 men. Recruits join the ranks in an elaborate swearing-in ceremony in the Vatican’s apostolic palace. Each new guard grasps the corps’ flag, raising three fingers in a symbol of the Holy Trinity and swears to uphold the Swiss Guard oath to protect the pope and his successors. The ceremony is held each May 6 to commemorate the Sack of Rome.