Frederick I, Holy Roman Emperor, was willing to arbitrate the conflict between Géza II and Stephen, and dispatched his envoys to Hungary.
In response, Géza sent delegates to the Emperor.
Frederick I initially contemplated that "the dispute must be terminated either by a division of the realm or by the condemnation of one or the other", but finally "decided to defer to a more suitable time the settlement of this quarrel", because he was planning to invade Italy.
As a result, with Frederick I's consent, Stephen left for Constantinople, as documented by Niketas Choniates, a contemporary historian, who wrote that Stephen fled "from the murderous clutches of his brother".

The Byzantine Emperor Manuel I Komnenos welcomed him and arranged Stephen's marriage with his niece Maria Komnene.
According to Gerhoh of Reichersberg, Stephen converted to the Orthodox Church on this occasion.
Stephen's brother, Ladislaus, also arrived in Constantinople around 1160, but he refused to marry a relative of the Emperor.

Manuel I, whose main concern was the insecurity of his empire's eastern frontier at that time, would not assist Stephen, therefore Stephen set out and again visited Emperor Frederick I in Parma, at some point near the end of 1160 or the beginning of 1161.
He promised Frederick I "to pay him 3,000 marks every year" if the Emperor assisted him in obtaining Hungary.
When Frederick, who was making preparations for the siege of Milan, did not promise any assistance to Stephen, he soon returned to Constantinople. (
According to historian Paul Stephenson this episode happened in March 1164.)

Géza II died on 31 May 1162.
Within days, his 15-year-old son, Stephen III, was crowned king by Lucas, Archbishop of Esztergom.
Emperor Manuel I sent envoys to Hungary to promote the elder Stephen's claim to the crown against the young King, however, the Hungarian lords opposed him, because "they deemed it disadvantageous to join with a man who was related to the emperor by marriage and feared that as Hungarians they would be governed by him as king while he was ruled" by Emperor Manuel.
Stephen returned to Hungary accompanied by a Byzantine army under the command of Alexios Kontostephanos.
The Byzantine army marched as far as Haram (now Ram, Serbia), where new negotiations were opened between the Byzantine envoys and the Hungarian lords.
They worked out a compromise agreement: the Hungarian lords acknowledged the claim of Stephen's elder brother, Ladislaus, to the crown, forcing Stephen III to flee to Austria six weeks after his coronation.
Frederick I, Holy Roman Emperor, was willing to arbitrate the conflict between Géza II and Stephen, and dispatched his envoys to Hungary. In response, Géza sent delegates to the Emperor. Frederick I initially contemplated that "the dispute must be terminated either by a division of the realm or by the condemnation of one or the other", but finally "decided to defer to a more suitable time the settlement of this quarrel", because he was planning to invade Italy. As a result, with Frederick I's consent, Stephen left for Constantinople, as documented by Niketas Choniates, a contemporary historian, who wrote that Stephen fled "from the murderous clutches of his brother".
The Byzantine Emperor Manuel I Komnenos welcomed him and arranged Stephen's marriage with his niece Maria Komnene. According to Gerhoh of Reichersberg, Stephen converted to the Orthodox Church on this occasion. Stephen's brother, Ladislaus, also arrived in Constantinople around 1160, but he refused to marry a relative of the Emperor.
Manuel I, whose main concern was the insecurity of his empire's eastern frontier at that time, would not assist Stephen, therefore Stephen set out and again visited Emperor Frederick I in Parma, at some point near the end of 1160 or the beginning of 1161. He promised Frederick I "to pay him 3,000 marks every year" if the Emperor assisted him in obtaining Hungary. When Frederick, who was making preparations for the siege of Milan, did not promise any assistance to Stephen, he soon returned to Constantinople. (According to historian Paul Stephenson this episode happened in March 1164.)
Géza II died on 31 May 1162. Within days, his 15-year-old son, Stephen III, was crowned king by Lucas, Archbishop of Esztergom. Emperor Manuel I sent envoys to Hungary to promote the elder Stephen's claim to the crown against the young King, however, the Hungarian lords opposed him, because "they deemed it disadvantageous to join with a man who was related to the emperor by marriage and feared that as Hungarians they would be governed by him as king while he was ruled" by Emperor Manuel. Stephen returned to Hungary accompanied by a Byzantine army under the command of Alexios Kontostephanos. The Byzantine army marched as far as Haram (now Ram, Serbia), where new negotiations were opened between the Byzantine envoys and the Hungarian lords. They worked out a compromise agreement: the Hungarian lords acknowledged the claim of Stephen's elder brother, Ladislaus, to the crown, forcing Stephen III to flee to Austria six weeks after his coronation.
Stephen IV of Hungary