Lampert was the third son of the future King Béla I of Hungary and his Polish wife. He was born in Hungary when his father had already returned from Poland and had already received the Tercia pars regni in appanage from his brother, King Andrew I of Hungary.
The parties, however, wanted to avoid the civil war. Therefore they accepted the mediation services of the bishops, and they made an agreement (20 January 1064) in Győr. In the next years, the three dukes collaborated successfully with King Solomon, but afterwards new conflicts emerged among them.
The three dukes rebelled against the king and the eldest of them, Géza, was proclaimed king following their victory over Solomon"s troops (14 March 1074).
He invited Saxon settlers to his province and founded Lampertszász that became the nucleus of the future Beregszász (today Berehove in Ukraine). Lampert founded the a monastery for the White Canons in Titel (today in Serbia).
