Editing Stephen V of Hungary (section)

===Duke of Transylvania and Styria (1257–1260)===
When Stephen attained the [[age of majority]] in 1257, his father appointed him [[Duke of Transylvania]].{{sfn|Makk|1994|p=294}}{{sfn|Sălăgean|2005|p=234}} Stephen's rule in Transylvania was short-lived, because his father transferred him to [[Duchy of Styria|Styria]] in 1258.{{sfn|Bartl|Čičaj|Kohútova|Letz|2002|p=32}}{{sfn|Sălăgean|2005|p=234}} Styria had been annexed in 1254, but the local lords rose up in rebellion and expelled Béla IV's governor, [[Stephen I Gutkeled|Stephen Gutkeled]], before Stephen's appointment.{{sfn|Érszegi|Solymosi|1981|pp=154, 156}} Stephen and his father jointly invaded Styria and subdued the rebels.{{sfn|Érszegi|Solymosi|1981|p=156}} In addition to Styria, Stephen also received two neighboring counties—[[Vas County (former)|Vas]] and [[Zala County (former)|Zala]]—in Hungary from his father.{{sfn|Érszegi|Solymosi|1981|p=156}}{{sfn|Zsoldos|2007|pp=16–17}} He launched a plundering raid in [[Duchy of Carinthia|Carinthia]] in the spring of 1259, in retaliation of Duke [[Ulrich III, Duke of Carinthia|Ulrich III of Carinthia]]'s support of the Styrian rebels.{{sfn|Érszegi|Solymosi|1981|p=156}}{{sfn|Kristó|2003|p=177}}

Stephen's rule remained unpopular in Styria. With support from King [[Ottokar II of Bohemia]], the local lords again rebelled.{{sfn|Engel|2001|p=107}} Stephen could preserve only [[Pettau]] (present-day Ptuj, Slovenia) and its region.{{sfn|Kristó|2003|pp=177–178}} On 25 June 1260, Stephen crossed the river [[Morava (river)|Morava]] to invade Ottokar's realm.{{sfn|Kristó|2003|p=178}} His military force, which consisted of [[Székelys|Székely]], [[Romanians|Romanian]] and Cuman troops, routed an Austrian army.{{sfn|Kristó|2003|p=178}}{{sfn|Sălăgean|2005|p=235}} However, in the decisive [[Battle of Kressenbrunn]] King Béla's and Stephen's united army was vanquished on 12 July, primarily because the main forces, which were under King Béla's command, arrived late.{{sfn|Sălăgean|2005|p=235}}{{sfn|Érszegi|Solymosi|1981|p=157}} Stephen, who commanded the [[advance guard]], barely escaped from the battlefield.{{sfn|Zsoldos|2007|p=17}} The [[Peace of Vienna (1261)|Peace of Vienna]], which was signed on 31 March 1261, put an end to the conflict between Hungary and Bohemia, forcing Béla IV to renounce of Styria in favor of Ottokar II.{{sfn|Érszegi|Solymosi|1981|p=157}}