Short answers, pulled from the story.
Louis XI of France retained a Swiss company for his personal guard in 1480. By 1496 the unit had grown to about one hundred guardsmen and approximately twenty-seven officers and sergeants, formally known as the Cent Suisses.
Of the roughly nine hundred Swiss Guards defending the Tuileries Palace on the 10th of August 1792, about six hundred were killed in the fighting or massacred after surrendering. An estimated one hundred and sixty more died in prison or during the September Massacres that followed.
The Lion of Lucerne is a monument designed by sculptor Bertel Thorvaldsen and dedicated in 1821. It commemorates the Swiss Guards killed at the Tuileries in August and September 1792, naming twenty-six officers and recording that approximately 760 guardsmen died on those days.
The first Swiss Federal Constitution of 1848 and a federal law of 1859 outlawed Swiss military service abroad, with the Pontifical Swiss Guard as the sole exception. The exemption rests on a special accord between Switzerland and the Holy See recognizing the Vatican's unique status.
The Pontifical Swiss Guard was established in 1506, making it one of the oldest military units in the world. It is also recognized as the smallest army in the world, and today serves as both a ceremonial unit and a personal bodyguard for the Pope.
Swiss mercenary regiments served in seventeen different armies in total. Courts that employed Swiss Guard units included France, Prussia, Sardinia, the Dutch Republic, Genoa, Lucca, the Electoral Palatinate, the Duchy of Lorraine, and Egypt, among others.