After the death of the most powerful oligarch, Matthew Csák, in 1321, Charles became the undisputed ruler of the whole kingdom, with the exception of Croatia where local noblemen were able to preserve their autonomous status.

[14] Dante Alighieri wrote of "the schemes and frauds that would attack"[15] Charles Martel's family in reference to Robert's alleged manoeuvres to acquire the right to inherit Naples.

[16] Andrew III of Hungary made his maternal uncle, Albertino Morosini, Duke of Slavonia, in July 1299, stirring up the Slavonian and Croatian noblemen to revolt.

[17][18] A powerful Croatian baron, Paul Šubić, sent his brother, George, to Italy in early 1300 to convince Charles II of Naples to send his grandson to Hungary to claim the throne in person.

[24][22] Charles counted his regnal years from this coronation, but Hungary had actually disintegrated into about a dozen independent provinces, each ruled by a powerful lord, or oligarch.

[26][27][28] Among them, Matthew Csák dominated the northwestern parts of Hungary (which now form the western territories of present-day Slovakia), Amadeus Aba controlled the northeastern lands, Ivan Kőszegi ruled Transdanubia, and Ladislaus Kán governed Transylvania.

[31] However, most Hungarian lords continued to oppose Charles because, according to the Illuminated Chronicle,[32] they feared that "the free men of the kingdom should lose their freedom by accepting a king appointed by the Church".

[25] Charles's charters show that he primarily stayed in the southern parts of the kingdom during the next years although he also visited Amadeus Aba in the fortress of Gönc.

[48] In the same year, Ugrin Csák died, enabling Charles to take possession of the deceased lord's domains, which were situated between Požega in Slavonia and Temesvár (present-day Timișoara in Romania).

[49] The united forces of the Abas and Matthew Csák besieged Kassa, but Charles routed them in the Battle of Rozgony (now Rozhanovce in Slovakia) on 15 June 1312.

[53] In July, Charles captured the Abas' many fortresses in Abaúj, Torna and Sáros counties, including Füzér, Regéc, and Munkács (now Mukacheve in Ukraine).

[58] No primary source has made reference to Charles's bravery or heroic acts, suggesting that he rarely fought in person in the battles and sieges.

[63][64] After Charles neglected to reclaim Church property that Matthew Csák had seized by force, the prelates of the realm made an alliance in early 1318 against all who would jeopardize their interests.

[61] The last Diet during Charles's reign was held in 1320; following that, he failed to convoke the yearly public judicial sessions, contravening the provisions of the Golden Bull.

[71][72] About three months later, Charles's new voivode of Transylvania, Thomas Szécsényi, seized Csicsó (present-day Ciceu-Corabia in Romania), the last fortress of Ladislaus Kán's sons.

[57][76] In the same year, the Dukes of Austria renounced Pressburg (now Bratislava in Slovakia), which they had controlled for decades, in exchange for the support they had received from Charles against Louis IV, Holy Roman Emperor, in 1322.

[78] Although Basarab was willing to accept Charles's suzerainty in a peace treaty signed in 1324, he refrained from renouncing control of the lands he had occupied in the Banate of Severin.

[95] During his reign, five new "chambers" (administrative bodies headed by German, Italian or Hungarian merchants) were established for the control and collection of royal revenues from coinage, monopolies and custom duties.

[102] On 21 September 1328, Charles signed a peace treaty with the three dukes of Austria (Frederick the Fair, Albert the Lame, and Otto the Merry), who renounced Pressburg and the Muraköz (now Međimurje in Croatia).

[77] After being defeated by the united forces of the Teutonic Knights and John of Bohemia, Władysław I sent his son and heir, Casimir, to Visegrád in late 1329 to seek assistance from Charles.

[81] In summer 1335, the delegates of John of Bohemia and the new King of Poland, Casimir III, entered into negotiations in Trencsén to put an end to the conflicts between the two countries.

[123] The three rulers agreed upon a mutual defence union against the Habsburgs, and a new commercial route was set up to enable merchants travelling between Hungary and the Holy Roman Empire to bypass Vienna.

[130] Two leading Polish lords, Zbigniew, chancellor of Cracow, and Spycimir Leliwita, also supported this plan and persuaded Casimir III, who lost his first wife on 26 May 1339, to start negotiations with Charles.

[80] The following year, Charles also forced Donch to renounce his two fortresses in Zólyom in exchange for one castle in the distant Kraszna County (in present-day Romania).

[108] The Anonymi descriptio Europae orientalis ("An Anonymous' Description of Eastern Europe"), written in the first half of 1308, claims that "the daughter of the strapping Duke of Ruthenia, Leo, has recently married Charles, King of Hungary".

[144] Historian Gyula Kristó says, the three documents show that Charles married a daughter of Leo II of Galicia in late 1305 or early 1306.

[146] The Polish scholar, Stanisław Sroka, rejects Kristó's interpretation, stating that Leo I—who was born in 1292, according to him—could hardly have fathered Charles's first wife.

[150][151] The Illuminated Chronicle recorded that she died on 15 December 1317, but a royal charter issued on 12 July 1318 stated that her husband made a land grant with her consent.

[152] Charles's next—second or third—wife was Beatrice of Luxembourg, who was a daughter of Henry VII, Holy Roman Emperor, and the sister of John, King of Bohemia.

[108] In particular, the unusual cruelty that the king showed after Felician Záh's assassination attempt on the royal family contributed to the negative picture of Charles's personality.