After his father's death, a throne struggle broke out between Konstantin, Stefan and their cousin Vladislav II, evolving into the two years long civil war.

Apparently not much valued by his contemporaries, even by his own father who appointed him a successor only when had no other options, he met a cruel death by the hand of his own brother, losing the throne to which he lawfully succeeded.

[6] Aleksa Ivić placed Konstantin as the youngest child of Milutin, while giving birth date of c. 1274 for his brother Stefan Dečanski.

[8] Vladimir Ćorović claimed that Konstantin was the older son, while he considered Stefan Dečanski a child of Milutin's fourth wife Anna,[9] who married the king in 1284.

Also pushed by the local nobility, Stefan started the rebellion against his father in 1314 which was quickly quashed with Milutin personally heading the army.

[9] Silver coins represented Konstantin sitting on the throne had inscriptions "Dominus rex Constantinus" and "Sanctus Stefanus Scutari" on the obverse and reverse, respectively.

[9][27] After 7 years, under the influence of clergy and especially of Serbian archbishop Nikodim I, Milutin allowed Stefan Dečanski to return to Serbia from Constantinople in 1321.

[23] Danilo II, Serbian archbishop and one of the main medieval chroniclers, was the staunch supporter of Stefan Dečanski and wrote that Milutin left no official successor as he lost ability to speak due to his illness.

[30] Stefan Dečanski, who was in Serbia, upon hearing the news of his father's death, took down the bandages from his eyes (which he kept for years, pretending to be blind) and declared that Saint Nicholas miraculously restored his sight.

He prepared himself well, he was a favorite of the church, his life was seen as an ordeal and martyrdom by the population who believed his miraculous healing, and he was of fully Slavic origin.

By the next year, the highest ranked members of the clergy officially turned back on Konstantin and archbishop Nikodim II crowned Stefan Dečanski on the Epiphany, 6 January 1322, in the Žiča monastery.

[24][35] With Vladislav II, claiming the title since 12 March 1316, and Konstantin, succeeding to Milutin on 29 October 1321, Serbia now had three proclaimed kings, which was a situation that couldn't last for long.

[36] Also, Konstantin thought he would prevail due to the army of foreign mercenaries he organized on his father's orders, starting with his visit to Constantinople in 1321.

[9] From the outside, Stefan was supported by the Byzantines, as during his exile in Constantinople he was sheltered by the emperor Andronikos II Palaiologos and later, after he secured Serbian throne, he married Andronik's great-niece Maria.

Having much larger support than Konstantin (rulers of Hungary and Bosnia, local nobility), Vladislav proved out to be also a tougher opponent.

A 1332 work, variously attributed to the Dominican Pseudo-Brocard, or to the Roman Catholic cleric Guillaume Adam, depicts Konstantin's more gruesome ending.

[42] Also, the entire chronicle has strong anti-Stefan sentiment while Adam was notorious for his negative attitude towards Serbs, calling them the "snake batch".

[38][43] This manner of death resembles the Biblical tale of the Crucifixion of Jesus, and as Stefan had no reason to make a martyr out of Konstantin, it is believed that Adam fabricated the story altogether.

Ragusan chronicler Mavro Orbini adopted Adam's account in his 1601 Kingdom of the Slavs,[44] but makes a point that it was actually Vladislav who captured and tortured Konstantin.

According to the folk poetry, recorded by Vuk Karadžić, the mercenaries bribed by Stefan Dečanski were those who nailed him to the plank and sawed him in half, throwing the remains into the river (Ibar ?).

[39] Folk myths tell stories of Stefan beheading Konstantin, silver plating his skull into the cup and drinking wine from it.

[45] Close to Zvečan is the Banjska Monastery, the endowment and planned burial church of his father, king Milutin, so it is believed that Konstantin was buried there.

[37] Konstantin was mentioned in several Serbian medieval chronologies and genealogies (rodoslov): Koporinjski, Studenički, Cetinjski, Vrhobreznički, Senički.

However, in the large Nemanjić family tree fresco in the monastery of Visoki Dečani, built by his brother Stefan who defeated him, Konstantin is not present.

[51] The Vasojevići, one of the Serbian Highland tribes of Montenegro, and their progenitor Vaso, were mentioned for the first time in a document found in an Ragusan archive, dated to 1444.

[53] Given the importance of the Vasojevići, especially of their diaspora, and following the myth of their origin which exists only in oral tradition though, the historic and modern descendants of Stefan Konstantin would be rebellion leader Karađorđe,[54] brothers footballers and co-founders of Galatasaray Milija and Pavle Bakić,[55] politician Slobodan Milošević, model and actress Milla Jovovich[56] or tennis player Jelena Janković.