Swiss Guards celebrate 517 years in 2023.

The Vatican will hold its annual ceremony to swear-in new recruits into the Swiss Guards, the world's smallest army, on Saturday 6 May.

The pomp-filled event, held in the S. Damaso courtyard of the Apostolic Palace, will see 23 new guards take a solemn oath of allegiance to the pope.

The annual ceremony commemorates 6 May 1527, when 147 Swiss Guards died protecting Pope Clement VII from the army of the Holy Roman Emperor.

• Swiss Guards: a brief history of the pope's army

The pope fled via the 800-m Passetto di Borgo passageway to the nearby refuge of Castel S. Angelo.

Led by Commander Christoph Graf, the current Swiss Guards belong to the world's oldest standing army which celebrated its 517th anniversary on 22 January this year.

The guards must be male and of Swiss nationality, as well as being Catholic, unmarried and aged between 19 and 30.

They must also have undergone intensive Swiss military training and be a minimum height of 174 cm.

In addition to protecting the pope, the army performs ceremonial duties and assists at Vatican functions, and is famous for its ancient halberd weapons and its blue, gold and red uniform.

The soldiers generally serve for between two and 25 years at the Vatican, in the service of the pope.