Pope Julius II was Bishop of Lausanne years earlier so he asked the Swiss cantons to provide him with a standing corps of 200 men for the defense of the Papal State.
The Pontifical Swiss Guard, as a defensive force of the Vatican City, was formed on this day in 1506, during the time of Pope Julius II (born Giuliano della Rovere). This pope, who was the Bishop of Lausanne years earlier, asked the Swiss cantons to provide him with a standing corps of 200 men for the defense of the Papal State.
The Swiss responded and, on this day, the first contingent of 150 soldiers arrived in Rome. That is why this day is symbolically considered the beginning of the Papal Swiss Guard. Just to mention, many European courts during history had Swiss Guards. Namely, Switzerland used to be a relatively poor Alpine country, so its young men were forced to seek employment in other countries as mercenaries. The Swiss Guard of the French king Louis XVI, for example, was the last to remain defending the king during the French Revolution and was killed almost to the last man.
The Pontifical Swiss Guard is today the last of its kind. Today, it consists of 135 members as follows: 99 halberdiers, 31 NCOs, 3 officers, 1 chaplain, and 1 Commandant (bearing the rank of Colonel).