Duke in Hungary (c. 1048–1060)
Upon leaving Poland, Andrew and Levente settled in Kiev. They returned to Hungary after a rebellion which was dominated by pagans broke out against King Peter Orseolo in 1046. The King was dethroned, and Andrew was proclaimed king. Levente died in the same year and Andrew, still childless, decided to invite Béla back to Hungary.
Having lost one brother, King Andreas sent to Poland to his other brother Bela, calling him with great love and saying: "Once we shared poverty and labour together, and now I ask you, most beloved brother, that you come to me without tarrying, so that we may be companions in joy and share in the good things of the kingdom, rejoicing in each other's presence. For I have neither heir nor brother except you. You shall be my heir, and you shall succeed me in the kingdom." Won by these words, Béla came to the King with all his family. When the King saw him, he rejoiced with a great joy, because he was fortified by his brother's strength. Then the King and his brother Bela held a council and divided the kingdom into three parts, of which two remained under the proprietorship of the royal majesty or power and the third was put under the proprietorship of the Duke. This first division of the kingdom became the seed of discord and wars between the dukes and the kings of Hungary.
Urged by his brother, Béla returned in 1048 and received one-third of the kingdom, with the title of duke. Béla's ducatus or "duchy" encompassed large territories along the eastern and northern borders, including the regions of Nyitra (Nitra, Slovakia) and Bihar (Biharia, Romania). He possessed a wide range of royal prerogatives, including coinage. The half-denars minted for him bore the inscription BELA DUX ("Duke Béla"). According to Steinhübel, the mid-11th-century timber and earth walls of the fortress of Nyitra were erected in Béla's reign.
The two brothers closely collaborated in the subsequent years. According to the Illuminated Chronicle, they together worked out a military strategy against the Germans, who were frequently invading the kingdom in the early 1050s. Ferenc Makk writes that Béla's epithets—the Champion or the Wisent—are connected to his fighting against the Germans. The chronicler emphasizes that Andrew and Béla "lived in a great tranquillity of peace" even after Andrew fathered a son, Solomon, in 1053. Béla was one of the lords witnessing the deed of the foundation of the Tihany Abbey, a Benedictine monastery that his brother established in 1055.
The two brothers' good relationship deteriorated after King Andrew had the child Solomon crowned king in 1057 or 1058. The coronation was the consequence of the peace negotiations with the Holy Roman Empire, because the Germans did not acquiesce in a marriage between Solomon and Judith—the sister of the young German monarch, Henry IV—until Solomon's right to succeed his father was declared and publicly confirmed. Thereafter Andrew was determined to secure the throne for his son. He invited Béla to his manor in Tiszavárkony, where the King offered his brother a seemingly free choice between a crown and a sword (which were the symbols of the royal and ducal power, respectively). However, he had ordered that Béla be murdered if he chose the crown. Having been informed of his brother's secret plan by one of his own partisans in the royal court, Béla opted for the sword, but he departed for Poland after the meeting.
He returned to Hungary, in the autumn of 1060, with Polish troops that Duke Boleslaus the Bold of Poland had provided. Around the same time, German reinforcements arrived in Hungary to assist Andrew against Béla. The ensuing civil war ended with the victory of Béla, who defeated his brother in two successive battles fought at the river Tisza and at Moson. The King was seriously injured and died soon afterward. His partisans took his son, the child Solomon, to Germany.
