Leader of the Bohemian Revolt

Despite his accession to the crown of Bohemia in 1617, Ferdinand was not willing to agree to the demands of the Bohemian nobility. Furthermore, their demands also failed to prevent Ferdinand's election as Holy Roman Emperor in 1619. What the nobles did achieve was that in 1618, in a stormy event at the Royal Castle of Prague, count Thurn was a key leader of that faction of the nobility who incited a crowd that defenestrated two of Ferdinand's representatives, Jaroslav Bořita of Martinice and Vilém Slavata of Chlum together with their scribe, Philip Fabricius.^[3]

Following the defenestration, Thurn was elected as one of the thirty Defenders of the Protestant Faith elected by the Estates of Bohemia. The revolt of the Protestant population of Bohemia began on 23 May 1618 and Thurn took command of the national army.^[4] His command was signified by a series of ineffective campaigns, faults in the campaign plan in some cases beyond his control, which frustrated imperial efforts to quickly crush the revolt.^[5] He participated in deposing Ferdinand of Bohemia from the throne and in the election of Frederick V, Elector Palatine as the new Bohemian king. Count Thurn was commander of a regiment at the inauspicious Battle of White Mountain in 1620. After the Bohemians' defeat there, Ferdinand exiled him, like all the other Protestant nobility (including leaders of the uprising) and townspeople. Consequently, Thurn lost his estates in Bohemia.

In exile

After being exiled, Thurn continued to take part in the fighting and political negotiations of the Thirty Years' War against the Habsburgs, acting in the roles of both diplomat and as a soldier.

In 1626 he took command of some troops in Silesia. Then he served as lieutenant general in the army of King Gustav Adolf of Sweden. His only son, count František Bernard, who rose to the rank of colonel in Swedish service, fell ill during the Polish campaign and died in 1628.

On 11 October 1633 Thurn and his force of 8,000 soldiers were confronted by Wallenstein's army near Steinau an der Oder in Saxony, where he was captured. He was ransomed soon from the captivity, and retired to the family's new holdings in Pärnu (Pernau), Estonia. Count Thurn died there, and was buried in the St. Mary's Cathedral of Tallinn.

His heir was his underage grandson, count Heinrich von Thurn-Valsassina of Pärnu (1628–1656), son of František Bernard (1592–1628) and Magdalena von Thurn-Valsassina (born von Hardeck).

Count Thurn wrote a booklet in German, titled Defensionsschrift ("Writing about Defenestration"), the work justifying his role in the events of 1618 as a deliberate, conscious defence of his religious beliefs. The booklet was published in Sweden.