Centuries ago, the Swiss Cantons had about 500,000 inhabitants and formed an overpopulated country, where, because of the precarious economic conditions of the times, there was much poverty. There was no choice but to emigrate and one of the most profitable jobs was that of a mercenary soldier abroad. There were some 15,000 men available for this type of work which was “organized” and controlled by the small Confederation of Cantons. They were the best troops of those times. Without cavalry and with little artillery, they had invented a tactic of movement that was superior to all others.
Pope Sixtus IV made alliance in 1497 with the Confederates, which foresaw the possibility of recruiting mercenaries, and he had barracks built for them. Later, renewing the old pact, Innocent VIII (1484-1492) also desired to make use of them against the Duke of Milan. January 22nd, 1506, is the official date of birth of the Pontifical Swiss Guard, as on that day, towards the evening, a group of one hundred and fifty Swiss soldiers commanded by Captain Kasparvon Silenen, of Canton Uri, passed through the Porta del Popolo and entered for the first time the Vatican, where they were blessed by Pope Julius II.
On the morning of May 6th, 1527, Captain General Bourbon launched a series of attacks on Rome. The Spanish mercenaries broke through the Torrione Gate. The Swiss Guard, standing firm resisted desperately. Their Captain, Kaspar Röist was wounded, and later killed by the Spaniards. Of the 189 Swiss Guards, only 42 survived, the ones who, when all was lost, under the command of Hercules Göldli guarded Pope Clement VII’s retreat to safety in Castel Sant’Angelo.
Tradition continues and today the tiny force is responsible for the Pope’s safety, including the security of the Apostolic Palace, and acts as the de facto armed forces of Vatican City, the world’s tiniest sovereign state. The 130 members of the Swiss Guard are required to be Catholic, unmarried Swiss citizens who have completed Swiss military service. They need to be at least 5ft 8in tall and between the ages of 19 and 30. The papal Swiss Guard tradition has been marching on for nearly 500 years — making it the oldest, continually active military corps in history.
Reference:
http://www.mapsofworld.com/on-this-day/january-22-1506-the-swiss-guards-arrive-at-the-vatican
http://www.vatican.va/roman_curia/swiss_guard/swissguard/storia_en.htm
This Day in History 