Sack of Rome ( 1527 ) The Sack of Rome on 6 May 1527 was a military event carried out by the mutinous troops of Charles V , Holy Roman Emperor in Rome , then part of the Papal States . It marked a crucial imperial victory in the conflict between Charles and the League of Cognac ( 1526 – 1529 ) — the alliance of France , Milan , Venice , Florence and the Papacy . Pope Clement VII had given his support to the Kingdom of France in an attempt to alter the balance of power in the region , and free the Papacy from dependency , i . e . a growing weakness to " Imperial domination " by the Holy Roman Empire ( and the Habsburg dynasty ) . The army of the Holy Roman Emperor defeated the French army in Italy , but funds were not available to pay the soldiers . The 34 , 000 Imperial troops mutinied and forced their commander , Charles III , Duke of Bourbon and Constable of France , to lead them towards Rome . Apart from some 6 , 000 Spaniards under the Duke , the army included some 14 , 000 Landsknecht s under Georg von Frundsberg , some Italian infantry led by Fabrizio Maramaldo , the powerful Italian cardinal , Pompeio Colonna and Luigi Gonzaga , and also some cavalry under command of Ferdinando Gonzaga and Philibert , Prince of Orange . Though Martin Luther himself was not in favor of it , some who considered themselves followers of Luther ' s Protestant movement viewed the Papal capital as a target for religious reasons , and shared with the soldiers a desire for the sack and pillage of a very rich city that appeared to be an easy target . Numerous bandits , along with the League ' s deserters , joined the army during its march . The Duke left Arezzo on 20 April 1527 , taking advantage of the chaos among the Venetians and their allies after a revolt which had broken out in Florence against the Medici . In this way , the largely undisciplined troops sacked Acquapendente and San Lorenzo alle Grotte , and occupied Viterbo and Ronciglione , reaching the walls of Rome on 5 May . The Sack . The troops defending Rome were not at all numerous , consisting of 8 , 000 militiamen led by Renzo di Ceri including 2 , 000 Papal Swiss Guard and 2 , 000 of Giovanni de ' Medici ' s Bande Nere . The city ' s fortifications included the massive walls , and it possessed a good artillery force , which the Imperial army lacked . Duke Charles needed to conquer the city hastily , 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 Hill s . 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 . One of the Swiss Guard ' s most notable hours occurred at this time . Almost the entire guard was massacred by Imperial troops on the steps of St Peter ' s Basilica . Of 189 guards on duty only the 42 who accompanied the pope survived , but the bravery of the rearguard ensured that Pope Clement VII escaped to safety , down the " Passetto di Borgo " , a secret corridor which still links 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 amok 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 . After three days of ravages , Philibert ordered the sack to cease , but few obeyed . In the meantime , Clement remained a prisoner in Castel Sant ' Angelo . Francesco Maria della Rovere and Michele Antonio of Saluzzo arrived with troops on 1 June in Monterosi , north of the city . Their cautious behaviour prevented them from obtaining an easy victory against the now totally undisciplined Imperial troops . On 6 June , Clement VII surrendered , and agreed to pay a ransom of 400 , 000 ducati in exchange for his life ; conditions included the cession of Parma , Piacenza , Civitavecchia and Modena to the Holy Roman Empire ( however , only the latter could be occupied in fact ) . At the same time Venice took advantage of his situation to capture Cervia and Ravenna , while Sigismondo Malatesta returned in Rimini . Aftermath . Emperor Charles V was greatly embarrassed by the fact that he had been powerless to stop his troops striking against Pope Clement VII and imprisoning him . Some may argue that Charles was partially responsible for the sack of Rome , because he expressed his desire for a private audience with Pope Clement VII and his men took action into their own hands . Clement VII was to spend the rest of his life trying to steer clear of conflict with Charles V , avoiding decisions that could displease him . Without any qualms and without conditions , Clement VII agreed to cede the worldly and political possessions of the bishopric of Utrecht to the Habsburgs . In the view of many at the time and since , fear of a repeat of the sack of Rome , along with the Pope ' s virtual imprisonment as a result of it , made it impossible for him to offend the Emperor by granting England ' s King Henry VIII the annulment that he sought of his marriage to the Emperor ' s aunt Catherine of Aragon , so Henry eventually broke with Rome , thus leading to the English Reformation . This event marked the end of the Roman Renaissance , damaged the papacy ' s prestige and freed Charles V ' s hands to act against the Reformation in Germany and against the rebellious German princes allied with Luther . Nevertheless , Martin Luther commented : " Christ reigns in such a way that the Emperor who persecutes Luther for the Pope is forced to destroy the Pope for Luther " ( LW 49 : 169 ) . The population of Rome dropped from some 55 , 000 before the attack , to a meagre 10 , 000 . An estimated 6 , 000 to 12 , 000 people were murdered . < br > Many Imperial soldiers also died in the following months ( they remained in the city until February 1528 ) from diseases caused by the large number of unburied dead bodies in the city . The pillage only ended when , after eight months , the food ran out , there was no one left to ransom and plague appeared . In commemoration of the Sack and the Guard ' s bravery , recruits to the Swiss Guard are sworn in on 6 May every year .