| John III | |
| Noble Family: | La Marck |
| Father: | John II, Duke of Cleves |
| Mother: | Mathilde of Hesse |
| Issue: | |
| Birth Place: | Deggendorf, Germany |
| Death Date: | 6 February 1539(aged 48) |
| Issue-Pipe: | Detail |
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| Spouse-Type: | Spouse |
John III, Duke of Cleves and Count of Mark (German: Johann III der Friedfertige; 10 November 1490 – 6 February 1539), known as John the Peaceful, was the Lord of Ravensberg, Count of Mark, and founder of the United Duchies of Jülich-Cleves-Berg.
John was born on 10 November 1490, as the son of John II, Duke of Cleves, and Mathilde of Hesse. In 1510, at the age of 19, John married Duchess Maria of Jülich-Berg, daughter of Duke William IV of Jülich-Berg and Sibylle of Brandenburg, who became heiress to her father's estates Jülich, Berg and Ravensberg.
John became ruler of the United Duchies of Jülich-Cleves-Berg in 1521, and Lord of Ravensberg in 1528. John represented a compensatory attitude, which strove for a Latin: via media between the two confessions during the Protestant Reformation. In fact, the real influence at the court of Cleves was Erasmus. Many of his men were friends and followers of the Dutch scholar and theologian. In 1532 John wrote up a list of church regulations(Kirchenordnung), which expressed numerous ideas of Erasmus.
John had an instinct for balance as was shown when he married his eldest daughter Sybille to the elector of Saxony, John Frederick. John Frederick would go on to later head the Schmalkaldic League. In many ways, John of Cleves' court was ideal for raising a queen. It was fundamentally liberal, but serious-minded, theologically inclined, and profoundly Erasmian. It was from this court that his daughter Anne would be raised. Anne became the fourth wife of King Henry VIII of England.
John and his wife Duchess Maria of Jülich-Berg had the following children: