Charles IV, Duke of Alencon (1489-1525) was an unimpressive French commander during the Italian Wars who became a scapegoat for the major defeat at Pavia in April 1525.
Charles was the son of René, Duke of Alencon, the third duke of the 1414 grant of the title, and Margaret of Vaudémont. Charles inherited his titles in 1492, while still an infant. He was close to the royal family, and in 1509 married Margaret of Angoulême, the sister of Francis, Duke of Valois.
Charles took part in the later Italian Wars of Louis XII. During the War of the League of Cambrai he fought against Venice at the battle of Agnadello (9 May 1509), and then took part in the unsuccessful French siege of Padua (August-September 1509). His marriage to Margaret came after the end of this siege.
In 1515 Francis came to the throne as Francis I. This meant that Charles was now First Prince of the Blood, the senior male member of the Valois dynasty after the King, his children and his grandchildren. He was also the king's brother in law. Inevitably he played a major part in Francis's wars in Italy, although never really gained an impressive reputation.
Francis's First Invasion of Italy (1515-16) was also his most successful. Alencon was part of the army, and fought at Francis's great victory of Marignano (13-14 September 1515). This gave Francis control of the Duchy of Milan.
In 1517 Alencon was made Duke of Berry as a reward for his services to the king.
The French position in Italy would be badly damaged in the First Hapsburg-Valois War (1521-26), the first clash between Francis I and the Emperor Charles V. Although the war began with French-supported attacks on their north-eastern and south-western borders, these went badly, and in the autumn an Imperial army invaded eastern France, threatening Champagne. Alencon played a major role in the defence against this invasion (although much of the credit goes to Pierre Terrail, seigneur of Bayard, who held the fortress of Mézières until Francis I appeared with the main French army).
In 1524, after the failure of a French invasion of Italy, Imperial forces invaded the south of France and besieged Marseille. Alencon was part of the army that Francis assembled at Lyons. This army lifted the siege and forced the Imperial troops to retreat back into Italy. Alencon held a senior command in the army that Francis led into Italy, and was present at the siege of Pavia (27 October 1524-24 February 1525). The city held out until an Imperial relief force appeared. The Imperial army then attacked Francis, inflicting a heavy defeat on him at the battle of Pavia (24 February 1525).
Alencon commanded about a third of the French army at Pavia, but his troops don't appear to have entered combat. After the capture of Francis Alencon was the senior French commander, and depending on your point of view either successfully retreated with the remnants of the battle or abandoned Francis to his fate without attempting to save his king. French opinion took the second view and Alencon was disgraced after his return to France.
Alencon died in April 1525, of a combination of pleurisy and grief after the defeat and his treatment in France. After his death Alencon's lands and titles went to his widow Marguerite. After her death they reverted to the crown.