https://medium.com/history-of-yesterday/why-does-the-vatican-have-swiss-guards-fb [login to see]
On January 22, 1506, the first contingent of 150 Swiss Guards arrived at the Vatican. From the article:
"Why Does The Vatican Have Swiss Guards?
The Swiss Guard is one of the oldest active military units in the world, stretching back to over 500 years. Who are the Pontifical Swiss Guard of the Holy See and what’s the unique history behind their tradition and loyalty to the Pope?
Born out of war
During the Middle Ages, Swiss mercenaries offered their services to foreign countries and cities. They were renowned for their poise and unquestionable loyalty to whomever they served and often died in the name of their employer. The Swiss Guard’s incorporation into the Papal States (sovereign states under the Pope’s rule) occurred in the early 1500s, amid the Italian Wars which were waged during the Renaissance, between 1494 to 1559.
In 1503, the same year he was elected, Pope Julius II recruited Swiss mercenaries. A few years later, on January 22, 1506, 150 more Swiss soldiers entered Rome, which formed the original Swiss Guard under the papacy. This particular Pope was liked among the Swiss, as he had been previously the Bishop of Lausanne in Switzerland from 1472 to 1476.
It was mostly France and Spain who fought for control over Italy’s sovereign states and surrounding territories, which included the Papal State of Rome. The sixty-five-year war ended with Spain being the dominant ruler for the next century and a half.
Surviving chaos
The Sack of Rome in 1527 exemplified the Swiss Guards’ loyalty. Pope Clement VII’s alliance with France angered Charles V, the King of Spain. In turn, Charles ordered his soldiers to siege Rome, and Clement VII was forced to crown him the Holy Roman Emperor. The safety of the Pope resulted in only forty-two guardsmen surviving out of the 189 enlisted. Afterward, the papal Swiss Guard became inactive. Only twelve out of the remaining forty-two Guards stayed to be a part of the group of Spanish and German mercenaries who took their place.
The end of the Italian Wars in 1559 precipitated sporadic disbandment and reinstatement of the papal Swiss Guard for over two centuries. The church’s uncertain future and implications due to relentless political conflict between bordering countries made it difficult for a stable papacy. The French Revolution lead to France’s invasion of the Papal States in 1798, which further weakened the church.
A new era
The church’s secular involvement ended in 1870, which once again reinstated the Swiss Guard and transitioned their role to mainly protecting the Pope and maintaining safety within the Vatican. After decades of the French occupying Rome, Italy took back the latter as its capital and the Papal States subsequently re-established itself as the Vatican — named after Vatican Hill located across the Tiber River. At this time, the Swiss Guard became a more impermeable fixture.
In 1929, the Vatican became its very own independent state under the Lateran Treaty between Italy and the Holy See (the Catholic church’s international governance). The treaty entailed that the church’s affairs and legalities are at its own discretion. In light of this, the Swiss Federal Council validated the Guard’s papal services as only a “simple security force” and are granted the means to operate without having to be regulated by the Swiss government.
Requirements
To be a Swiss Guard one must fulfill the following:
Swiss citizenship;
Catholic, with a priest’s endorsement;
Between 19 to 30 years old;
At least 174 cm tall (5 foot 8.5 inches);
Unmarried;
Completion of high school and/or a professional degree;
Completion of basic training in the Swiss army with a certificate of good conduct.
New guards are sworn in every year on May 6, which commemorates the exact date of the Sack of Rome almost 500 years ago. The length of service differs from two to twenty-five years and less than 125 soldiers are enlisted at any given time.
Uniform
Each uniform is personally fitted for each guard and it can take over thirty hours to make.
Their most popular ensemble, the Gala uniform, boasts the same colors as the aristocratic Medici family: red, blue, and yellow — which pays homage to the Guard’s early years under Popes Leo X (1513-1521) and Clement VII (1523-1534), both of whom were born Medici. Different variations of the Gala Uniform complement certain occasions, such as additional metal armor for Easter, Christmas, and swearing-in ceremonies.
A solid blue uniform is worn during training, night time, and near the entrance of the Vatican during the day to prevent distractions in traffic. Traditional weapons such as rapier swords are mainly for public show, while other weapons such as guns and pepper spray are concealed.
In 2019, 3D printed copies of the traditional sixteenth-century helmet were produced and are now part of the uniform. It only takes one day to produce the PVC copy, as opposed to 130 hours of metalwork.
Responsibilities
Aside from dutifully watching from all over the Vatican, the guards are present during all ceremonial events and receptions, as well as accompanying the Pope during his international travels. The Pontifical Gendarmeri is the official police force in the Vatican and they carry out the more concrete security measures. Pope Francis recently implemented a new task for the Swiss Guards: to gently counsel and refuse people who come soliciting requests and petitions.
The oath to be repeated when swearing-in:
'I swear I will faithfully, loyally and honourably serve the Supreme Pontiff and his legitimate successors and I dedicate myself to them with all my strength. I assume this same commitment with regard to the Sacred College of Cardinals whenever the Apostolic See is vacant. Furthermore, I promise to the Commanding Captain and my other superiors respect, fidelity and obedience. I swear to observe all that the honour of position demands of me.'”