5. As a second son of a Wallachian prince, Vlad was not expected to accede to the throne, as, by tradition, his older brother Mircea was the heir apparent. What event made Vlad the heir to the throne of Wallachia?
From Quiz Vlad Tepes
Answer:
His father and older brother were murdered
Vlad's father assumed the Wallachian throne in 1436. Vlad and his younger brother, Radu, were sent to the Ottoman court as hostages in 1442. In 1447, the Hungarian regent, John Hunyadi, invaded Wallachia and murdered Vlad's father and older brother, installing Vlad's cousin Vladislav II as Prince. Vlad reigned briefly in 1448, but had to flee. He courted both Ottoman and Hungarian support to regain his throne, which he finally won back in 1456.