Catherine de Medici was half French, half Italian. Orphaned in infancy, she was the sole legitimate heiress to the Medici family fortune. Married at fourteen to the future Henri II of France she was constantly humiliated by his influential mistress Diane de Poitiers. When her husband died as a result of a duelling accident Catherine became queen regent during the short reign of her eldest son. When her second son became king she was the power behind the throne. She nursed dynastic ambitions, but was continually drawn into political and religious intrigues. It had always been said that she was implicated in the notorious Saint Barthlomew’s Day Massacre, together with the king and her third son who succeeded to the throne in 1574, but was murdered – left standing with his assassin’s dagger in one hand, and his own entrails in the other. Her political influence waned, but she survived long enough to ensure the succession of her son-in-law who had married her daughter Margaret. Léonie Frieda has returned to original sources and re-read the thousands of letters left by Catherine. There has not been a biography in English of Catherine for many years and she believes that the time has come to show her as one of the most influential women in c16th Europe.