The world's oldest standing army has 40 new members after a Vatican Swiss Guard swearing-in ceremony. Each man took a loyalty oath Saturday evening in a ritual-rich ceremony in the St Damaso courtyard of the Apostolic Palace. The May 6 date commemorates the day in 1527 when 147 guardsmen died while protecting Pope Clement VII during the Sack of Rome. Earlier Saturday, Pope Francis told the Guards they are called to "another sacrifice no less arduous" — serving the power of faith. The recruits, who enroll for at least two years, must be single, upstanding Swiss Catholic males younger than 30. Wearing blue-and-gold uniforms and holding halberds — spear-like weapons — they are a tourist delight while standing guard at Vatican ceremonies. Their main duty is to protect the pope.