The growing power of Holy Roman Emperor Charles V alarmed Pope Clement VII, who perceived Charles as attempting to dominate the Catholic Church and Italy. In effort to free both from Imperial domination, Clement VII formed an alliance with Charles V’s arch-enemy, King Francis I of France, which came to be known as the League of Cognac (including France, Milan, Venice, Florence and the Papacy).
The imperial troops were 14,000 Germans, 6,000 Spanish, and an uncertain number of Italian infantry. The troops defending Rome were not at all numerous, consisting of 5,000 militiamen led by Renzo da Ceri and 189 Papal Swiss Guard. The city’s fortifications included the massive walls, and it possessed a good artillery force, which the Imperial army lacked. Charles III, Duke of Bourbon needed to conquer the city swiftly, to avoid the risk of being trapped between the besieged city and the League’s army.
On 6 May, the Imperial army attacked the walls at the Gianicolo and Vatican Hills. Duke Charles was fatally wounded in the assault, allegedly shot by Benvenuto Cellini. The Duke was wearing his famous white cloak to mark him out to his troops, but it also had the unintended consequence of pointing him out as the leader to his enemies. The death of the last respected command authority among the Imperial army caused any restraint in the soldiers to disappear, and they easily captured the walls of Rome the same day. Philibert of Châlon took command of the armies, but he was not as popular or feared, leaving him with little authority.
In the event known as the Stand of the Swiss Guard, the Swiss, alongside the garrison’s remnant, made their last stand in the Teutonic Cemetery within the Vatican. Their captain, was wounded and later sought refuge in his house, where he was killed by Spanish soldiers. The Swiss fought bitterly, but were immensely outnumbered and almost annihilated. Some survivors, accompanied by a band of refugees, fell back to the Basilica steps. Those who went toward the Basilica were massacred, and only 42 survived. This group of 42, under the command of Hercules Goldli, managed to stave off the Habsburg troops pursuing the Pope’s entourage as it made its way across the Passetto di Borgo, a secret corridor that still connects the Vatican City to Castel Sant’Angelo.
After the brutal execution of some 1,000 defenders of the Papal capital and shrines, the pillage began. Churches and monasteries, as well as the palaces of prelates and cardinals, were looted and destroyed. Even pro-Imperial cardinals had to pay to save their properties from the rampaging soldiers. On 8 May, Cardinal Pompeo Colonna, a personal enemy of Clement VII, entered the city. He was followed by peasants from his fiefs, who had come to avenge the sacks they had suffered by Papal armies. However, Colonna was touched by the pitiful conditions of the city and hosted in his palace a number of Roman citizens.
Often cited as the end of the Italian Renaissance, the Sack of Rome impacted the histories of Europe, Italy, and Catholicism, creating lasting ripple effects throughout world culture and politics.
Prior to the Sack, Pope Clement VII opposed the ambitions of Emperor Charles V and the Spanish, whom he correctly believed wished to dominate Italy and the Church; however, afterward he was no longer able to fight against them, lacking the military and financial resources to do so. To avert more warfare, the Pope adopted a conciliatory policy toward the Emperor. Charles V turned this to his political advantage, exerting increasing Imperial control over the Papacy and much of Italy.