Ladislaus prepared Coloman—who was "half-blind and humpbacked", according to late medieval Hungarian chronicles—for a church career, and Coloman was eventually appointed bishop of Eger or Várad (Oradea, Romania) in the early 1090s.

Hungarian chronicles, which were compiled in the reigns of kings descending from his mutilated brother and nephew, depict Coloman as a bloodthirsty and unfortunate monarch.

[11] The 14th-century Illuminated Chronicle stated that Coloman was "of mean stature, but astute and quick of apprehension", adding that he was "shaggy and hirsute, half-blind and humpbacked, and he walked with a limp and stammered in his speech".

[27] The same source adds that Álmos, "in the true simplicity of his heart honoured his brother, Coloman, and yielded to him the crown of the kingdom",[23] which suggests that he ascended the throne without bloodshed.

[16][29] This report shows that Álmos only acknowledged his brother's rule in exchange for receiving the duchy once held by their father and grandfather, an area that comprised one third of the territory of the kingdom.

[2][31] For decades, Hungary had been able to supply a significant number of Western European pilgrims with food during their journey to the Holy Land, but the movement of tens of thousands of crusaders across the country endangered the natives' subsistence.

[37][38] Peter himself claimed that he and his companions had passed through the country without incident until they reached Zimony, where they learnt of the story of the sixteen crusaders who had been robbed by the Hungarians.

[33][43] Coloman did not allow them to leave the region, either because he had learnt of their troublesome behavior during their journey, or he had realized that their movement across Hungary could jeopardize the stability of the local economy.

[43] Coloman decided to attack them, but the commanders of the army convinced him to persuade the crusaders to surrender their weapons and money, promising them that they would be supplied with food during their journey.

[33][43][46] [The crusaders] were even granted a licence to buy and sell necessary supplies, and peace was proclaimed on both sides according to [Coloman's] instructions, lest a dispute might arise from such a large army.

But when they were delayed there for some days, they began to wander, and the Bavarians and Swabians, a bold race, and the rest of the soldiers foolishly drank too much; they violated the proclaimed peace, little by little stealing wine, barley, and other necessities from the Hungarians, finally seizing sheep and cattle in the fields and killing them; they destroyed those who stood up to them and wanted to drive them out.

[50][51] According to Albert of Aix, contemporaneous Christians thought that Emicho's defeat was a punishment that God inflicted on the pilgrims because they had massacred many Jews "rather from greed for their money than for divine justice".

[53][54] The king allowed the crusaders to march through his kingdom but stipulated that Godfrey's younger brother Baldwin and his family should stay with him as hostages.

[59][61][62] Historian Nora Berend writes that the "defence of purity of Christians by interdictions against mingling with Jews plays a very minor role" in Coloman's legislation in comparison with late 12th-century canon law.

[65] After Coloman's victories over the crusaders, Henry IV, Holy Roman Emperor, whom Ladislaus I had supported against Pope Urban II in his last years, wrote a letter to Duke Álmos.

[73][28] Ladislaus I had already occupied most of the country, but Petar Snačić, the last native king of Croatia, resisted him in the Mala Kapela mountains.

[73][75] Threatened by the advance of Coloman's army, the citizens of the towns of Trogir and Split swore fidelity to the doge of Venice, Vitale Michiel, who had sailed to Dalmatia.

[75][70] Their agreement of 1098—the so-called Conventio Amicitiae—determined the spheres of interest of each party by allotting the coastal regions of Croatia to Hungary and Dalmatia to the Republic of Venice.

[83] Coloman and his army crossed the Carpathian Mountains and laid siege to Peremyshl (Przemyśl, Poland)—the seat of Volodar Rostislavich, one of the rebellious princes.

[82][88] He had a meeting with Bretislaus on the border river Olšava "in the field of Lučsko" where "they renewed their age-old bonds of friendship and peace and confirmed them with oaths",[89] according to Cosmas of Prague.

[73] However, the late 14th-century Pacta conventa narrates that he was only crowned after he had reached an agreement with twelve leading Croatian noblemen, because the Croats were preparing to defend their kingdom against him by force.

According to the historian Pál Engel, even if the document is a forgery, its content "is concordant with reality in more than one respect" concerning the special status of Croatia throughout the Middle Ages.

[106][107] The Life of St Christopher the Martyr also says that a Hungarian fleet subjugated the islands of the Gulf of Kvarner, including Cres, Krk, and Rab, as well as Brač.

[104] Having realized that the emperor, who was facing a rebellion led by his own son, could not help him,[104] Álmos returned to Hungary in 1106, but then fled to his brother-in-law, Boleslaw III of Poland.

[104][115] During the civil war between Boleslaw III and his brother Zbigniew, Coloman intervened on the former's behalf and helped him overcome the latter's army in Mazovia in 1107.

[113][119] The emperor's attempt to take Pressburg was a total failure, but he persuaded Coloman to forgive Álmos, who was allowed to return to Hungary.

[121] These two royal charters also mention a Mercurius as "princeps Ultrasilvanus", which implies he was the first voivode of Transylvania, but he may have been only an important landowner in the province without holding any specific office.

But the man who was instructed to blind them feared God and the sterility of the royal line, and therefore he castrated a dog and brought its testicles to the King.The fleet of Venice, commanded by Doge Ordelafo Faliero, invaded Dalmatia in August 1115.

[136] According to the Illuminated Chronicle, "divine vengeance made him drink the bitterness of early death" because of his "shedding of innocent blood"[137] when ordering the punishment of Álmos, Béla, and their partisans.

[1][23] Modern historians—including Font,[1] László Kontler,[3] and Kristó[134]—agree that this negative view was a form of "revenge" by his brother's descendants, who persuaded their chroniclers to emphasize Coloman's failures and to hide his successes.