Abel of Denmark (1218 – 29 June 1252) was Duke of Schleswig from 1232 to 1252 and King of Denmark from 1250 until his death in 1252. He was the son of Valdemar II by his second wife, Berengária of Portugal, and brother to Eric IV and Christopher I.

As Duke of Schleswig, Abel came into conflict with his brother, King Eric IV, whose murder in 1250 he was suspected of orchestrating. Upon taking an oath to clear himself of the allegations, he was elected king. After a short reign, he was killed during a military expedition in Frisia.

Abel's reign was the shortest of any Danish monarch since the 9th century. He founded a line of Dukes of Schleswig - the "Abel family" - which ruled the Duchy of Schleswig until 1375.

At the election in 1232 of his elder brother Eric as their father King Valdemar II's coruler and heir, Abel was chosen to succeed Eric in his position as Duke of Schleswig.

In 1237 he married Matilda of Holstein, a daughter of Adolf IV, Count of Holstein. As Count Adolf withdrew to a Franciscan friary the same year, Abel spent several years acting as regent for his under age brothers-in-law, John and Gerhard.

At the death of Valdemar II in 1241, Duke Abel's brother Eric acceded to the throne of Denmark as Eric IV. The following years Duke Abel fought against his brother, trying to gain independence for the Duchy of Schleswig. He raided north as far as Randers, ravaging Eric's supporters and then moved into Funen. Eric struck back a year later surprising Abel's garrison at Schleswig, forcing Abel's young daughter Sophie to flee "without so much as a pair of shoes for her feet."

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