He deposed his brother Iliaș I with the assistance several boyars and of the Wallachian Prince Vlad II Dracul.
[3] Iliaș was eventually freed in 1435, and returned at the head of an army, engaging his brother in several battles; the indecisive one in Podraga or Podagra (the present-day village of Podriga in Drăgușeni) brought Władysław III's mediation: an agreement was reached for Stephen and Iliaș to share the throne, with Stephen as ruler over the southeastern part of Moldavia, in Tecuci, Kilia, Vaslui, and Covurlui.
[4] In 1443, Iliaș breached their agreement, and Stephen caught him and gouged out his eyes.
Blinded, Iliaș sought refuge in Poland, while Stephen remained prince, taking as his associate an illegitimate brother, Petru II.
He was killed in 1447 by the son of Iliaș, Roman II, who had ensured Polish support during his refuge in Pokuttya.