He was first installed as a puppet king by the kingdom's leading noblemen, Hrvoje Vukčić Hrvatinić and Sandalj Hranić Kosača, to replace his increasingly dependent uncle Ostoja.

Tvrtko's second reign was marked by repeated Turkish raids, which forced him to accept the Ottoman suzerainty, and the struggle for power with Radivoj, another son of Ostoja.

Klaić cited as evidence Tvrtko I's charter of 1382, in which the King mentioned Queen Dorothea and an unnamed son to the government of the Republic of Ragusa.

The Council of the Kingdom, composed of the country's most prominent noblemen, elected his elderly relative, Dabiša, as his successor, rather than the deceased King's son, who was too young at the time.

At the end of April or the beginning of May, a stanak in Mile[8] was convoked in which the nobility deposed Ostoja, who fled to the court of the Hungarian king, Sigismund of Luxembourg.

[10][11] All major Bosnian noble families remained loyal to Tvrtko, while Ostoja functioned as Sigismund's puppet whose territory included little more than Bobovac.

[12] Sandalj, on the other hand, seized the opportunity to take over the land that belonged to Ostoja's favourites, the Sanković family, thus making the Kosačas the greatest landowners in the southern part of the kingdom.

When Hrvoje induced him to support King Ladislaus of Naples' claim to the Hungarian throne, Tvrtko became even more of a thorn in Sigismund's side.

The struggle between Ostoja and Tvrtko II for the Bosnian crown thus represents a phase of a much broader civil war between the supporters of Sigismund and Ladislaus.

[11] Following a few minor disputes with the maritime republics of Venice and Ragusa over Konavli and Pomorje, Tvrtko gained recognition as legitimate king from both states.

[11] The conflict culminated in September 1408, when Sigismund achieved a decisive victory over Tvrtko's troops: 170 minor noblemen were captured and killed in Dobor – tossed over the city walls.

[11] The hostilities continued until the end of November, with Tvrtko retreating southwards with his noblemen and resisting Hungarian attacks, which enabled Ostoja to reestablish control over Central Bosnia.

Ostoja seized the opportunity to try to reclaim the throne, but Sigismund too intended to have himself crowned King of Bosnia "in the solemn manner of Tvrtko I".

In December Ragusan officials wrote letters to him and his wife (of whom nothing is known) in response to his request of Saint Demetrius income; at the time he still resided in Bosnia.

[28] The internal troubles forced the Ottomans to withdraw their troops from Bosnia, which enabled Tvrtko to strengthen his hold on the kingdom and for its economy to recover.

[30] Tvrtko's second reign was marked by his quick resolution to restore royal authority and the king's pre-eminence among Bosnia's feudal rulers.

In 1422 Tvrtko signed a beneficial trade treaty with the Republic of Venice in December 1422, and discussed a range of plans for joint military action against Sigismund in Dalmatia.

[34] His attempts to find a suitable Catholic bride from the Venetian Malatesta family through the mediation of Peter of Pag, Archbishop of Split, were promising, but never materialized.

[33] Although the cooling of Tvrtko's relations with Venice suited Ragusa, another incident guaranteed that the city-state and the King would not be on friendly terms for some more time.

Ragusa had a long-standing tradition of granting political asylum to members of ruling families, and did not fail to accommodate Vuk when he sought sanctuary.

The same year, while the Turks were raiding the neighbouring Despotate of Serbia, Tvrtko decided to reclaim Srebrenica, which had been seized by Sigismund in 1411 and granted to his ally, the Serbian ruler Stefan Lazarević.

The local Ragusan merchants assisted the Serbs, and the project failed; Stefan's victorious troops went on to plunder Tvrtko's realm when the Turks retreated from their land.

Tvrtko's unfavourable position enabled Sigismund to demand the recognition of the latter's father-in-law, Hermann II of Celje, as heir presumptive to the childless king.

He was nominally supported by the Turks and by Stjepan Vukčić Kosača; they could have easily deposed Tvrtko in his favour if they wished, but it appears that their only goal was to weaken and divide Bosnia for their future benefit.

[33] Tvrtko died childless in November 1443, having expressed wish to be succeeded by his politically inactive and until then rather obscure cousin Thomas, Radivoj's younger brother and likewise an illegitimate son of Ostoja.

Given that the succession went smoothly, it can be assumed that Tvrtko actively worked on securing Thomas's accession, probably in order to ensure that his patrimony would not pass to the detested Radivoj.

[7] Tvrtko eventually married the Hungarian noblewoman Dorothy Garai, but not before assuring the papacy of his commitment to the Roman Catholic Church.