How did Ferdinand II learn about his deposition as king of Bohemia?
Through a letter from the Bohemian Estates
In the news
News reached Frankfurt when he was there
He was informed by Rudolf II
Answer
Ferdinand II learned about his deposition as king of Bohemia when news reached Frankfurt, where he was at the time. He was then forced to flee to Austria, where he continued to fight against the rebels.
Unveiling the Reign: The Remarkable Life of Ferdinand II, Holy Roman Emperor