Final answer:
Vlad II Dracul lost power in Wallachia due to Ottoman intervention, as the Ottomans expanded their territory and exerted control over the region. This happened against a backdrop of increasing Ottoman ascendancy in the Balkans during the 15th century.
Step-by-step explanation:
Vlad II Dracul lost power in Wallachia in 1442 primarily due to Ottoman intervention. The Ottomans, seeking to expand their influence, put pressure on the region's leaders. Vlad II was caught in the midst of this expansion. Complicated geopolitical manoeuvres eventually led to his losing power. Notably, during the period surrounding Vlad's loss of power, his sons, including Vlad III, known as Vlad the Impaler, were taken as hostages by the Ottomans as a part of a political agreement.
The loss of Wallachia's autonomy under Vlad II can be associated with the broader historical context involving the Ottoman Empire. The empire, known for its military expansions, gradually took control of various Balkan territories and clashed against European powers. While Wallachia's instability was not the result of a local rebellion, economic collapse, or natural disaster, it reflects the complex dynamics of power and sovereignty during the Medieval period, subsequently leading to shifts in control and confrontations with forces such as the Ottomans.