Charles III , Duke of Bourbon Charles III , Duke of Bourbon ( February 17 , 1490 – May 6 , 1527 ) was a French military leader , the Count of Montpensier and Dauphin of Auvergne . He commanded the Imperial troops of Holy Roman Emperor Charles V in what became known as the Sack of Rome in 1527 , where he was killed . Biography . Charles was born at Montpensier . His father , Gilbert , Count of Montpensier , died in 1496 , and his elder brother Louis II , Count of Montpensier , in 1501 , at which time he inherited the family lands in Auvergne . His mother was Clara Gonzaga ( 1 July 1464 - 2 June 1503 ) , a daughter of Federico I Gonzaga , Marquess of Mantua , and Margaret of Bavaria . On 10 May 1505 Charles married Suzanne , Duchess of Bourbon , the heir - general of the House of Bourbon ( of which he was the heir - male ) , and became Duke of Bourbon in her right . Already distinguished as a soldier in the Italian Wars , he was appointed Constable of France by Francis I of France in 1515 , and was rewarded for his services at the Battle of Marignano ( where he commanded the vanguard ) with the Governorship of Milan . However , Francis was uneasy with the proud and wealthy duke , and soon recalled him from Milan and refused to honor his debts . Charles was further angered by the appointment of Charles IV of Alençon , the King ' s brother - in - law , as commander of the vanguard during the campaigns in the Netherlands , an office which should have been his . The death of his wife in 1521 provoked the final breach . Suzanne had left all her estates to him , but the King ' s mother , Louise of Savoy , claimed them as the heir in proximity in blood , due to their previous entailments . She proposed to settle the question by marrying Charles ; but he refused the proposal . On behalf of his mother , Francis confiscated a portion of the Bourbon estates before the lawsuit had even been settled . Seeing no hope of prevailing , Charles made a secret agreement to betray his King and offer his services to the Holy Roman Emperor Charles V . The Emperor , the Constable , and King Henry VIII of England devised a grand plan to partition France , which came to nothing ; the plot was discovered and Charles was stripped of his offices and fled into Italy in 1523 . In 1524 , he drove the French under Bonnivet from Lombardy , and fought at the Battle of Pavia . The Emperor gave Duke Charles command of a mixed Spanish - German army ( which included a number of Lutherans ) sent to chastise Pope Clement VII . He neglected to supply this army with money or food , and Charles was only able to keep it together by promises of loot . Though Clement arranged a truce with the Emperor , the army continued its advance , reaching Rome in May , 1527 . The death of Duke Charles — the artist and goldsmith Benvenuto Cellini claimed that he fired the shot that killed him — outside the walls removed the last restraints from the army , which resulted in the sack of Rome . By Suzanne , Charles was the father of twins and of Francis of Bourbon , Count of Clermont . Officially , since none of them survived a year of age , the senior line of the Dukes of Bourbon was extinct in male line with his death in battle , and the junior line ( Dukes of Vendôme ) were not allowed to inherit , because Charles had forfeited his fiefs by committing treason . However , the county of Montpensier and dauphinate of Auvergne were later returned to his sister Louise . There is a very strong theory that believes that a fourth son was born in 1521 ( Louis Rousselet , Michel de Grece ) , Prince Jean Phillipe de Bourbon , Comte de Clermont , who was taken to safety in Italy and who would eventually be the founder of the Indian branch of the Bourbons ( see Bourbons of India ) . In conspiracy theories , such as the one promoted in " The Holy Blood and the Holy Grail " , he has been alleged to be the thirteenth Grand Master of the Priory of Sion , although he is only listed by his title .