|Born||10 November 1490|
|Died||6 February 1538 or 1539|
|Noble family||La Marck|
|Spouse(s)||Maria of Jülich-Berg|
|Father||John II, Duke of Cleves|
|Mother||Mathilde of Hesse|
John III, Duke of Cleves and Count of Mark (John III, Duke of Cleves; John I, Duke of Jülich-Berg; German: Johann III der Friedfertige, Herzog von Jülich-Kleve-Berg; 10 November 1490 – 6 February 1538 or 1539), called John the Peaceful, was a son of John II, Duke of Cleves and Mathilde of Hesse, daughter of Henry III, Landgrave of Upper Hesse.
John represented a compensatory attitude, which strove for a via media, a middle way, between the two confessions during the Protestant Reformation. Despite what others may have thought, not all Germanic princely houses were Lutheran Protestant. In fact the real influence at the court of Cleves was Erasmus. Many of his men were friends and followers of this well-educated Dutch scholar and theologian. When Duke John decided to write up a list of church regulations, Erasmus was the first person the Duke went to personally for consultation and approval.
Duke John had an instinct for balance as was shown when he married his eldest daughter Sybille to John Frederick of Saxony. 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, as the court of Catherine of Aragon had once been. It was from this court that his daughter Anne would be raised. Anne would go on to marry King Henry VIII of England as his fourth wife.
In 1509, he married Maria of Jülich-Berg, daughter of Duke William IV of Jülich-Berg and Sybilla of Brandenburg, who became heiress to her father's estates Jülich, Berg and Ravensberg. They had the following children:
- Sybille (17 January 1512 – 21 February 1554), married Elector John Frederick of Saxony, head of the Protestant Confederation of Germany, "Champion of the Reformation". Had issue.
- Anne (28 June 1515 – 16 July 1557), who was briefly married to King Henry VIII of England, as his fourth wife. No issue.
- William, Duke of Jülich-Cleves-Berg (28 July 1516 – 5 January 1592), married Maria, daughter of Emperor Ferdinand I, and had issue.
- Amalia (17 October 1517 – 1 March 1586)
|Ancestors of John III, Duke of Cleves|
- Morby, John (1989). Dynasties of the World: A chronological and genealogical handbook. Oxford University Press.
- Ward, A.W.; Prothero, G.W.; Leathes, Stanley, eds. (1934). The Cambridge Modern History. XIII. Cambridge at the University Press.
John III, Duke of ClevesBorn: 10 November 1490 Died: 6 February 1539
| Duke of Jülich-Berg
Count of Ravensberg
William the Rich
| Duke of Cleves|
Count of Mark