Catherine de' Medici (Italian: Caterina de' Medici, pronounced [kateˈriːna de ˈmɛːditʃi]; French: Catherine de Médicis, pronounced [katʁin də medisis]; 13 April 1519 – 5 January 1589), daughter of Lorenzo II de' Medici and of Madeleine de La Tour d'Auvergne, was an Italian noblewoman who was queen of France from 1547 until 1559, by marriage to King Henry II. As the mother of kings Francis II, Charles IX and Henry III, she had extensive, if at times varying, influence in the political life of France. From 1560 to 1563, she ruled France as regent for her son Charles IX, King of France.

In 1533, at the age of fourteen, Catherine married Henry, second son of King Francis I and Queen Claude of France. Throughout his reign, Henry excluded Catherine from participating in state affairs and instead showered favours on his chief mistress, Diane de Poitiers, who wielded much influence over him. Henry's death thrust Catherine into the political arena as mother of the frail fifteen-year-old King Francis II. When he died in 1560, she became regent on behalf of her ten-year-old son King Charles IX and was granted sweeping powers. After Charles died in 1574, Catherine played a key role in the reign of her third son, Henry III. He dispensed with her advice only in the last months of her life.

Catherine's three sons reigned in an age of almost constant civil and religious war in France. The problems facing the monarchy were complex and daunting but Catherine was able to keep the monarchy and the state institutions functioning even at a minimum level. At first, Catherine compromised and made concessions to the rebelling Calvinist Protestants, or Huguenots, as they became known. She failed, however, to grasp the theological issues that drove their movement. Later she resorted, in frustration and anger, to hard-line policies against them. In return, she came to be blamed for the excessive persecutions carried out under her sons' rule, in particular for the St. Bartholomew's Day massacre of 1572, in which thousands of Huguenots were killed in Paris and throughout France.

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