Why did the Bohemian Revolt begin after the death of Emperor Matthias in 1619?

The Bohemian Revolt began in 1618, prior to the death of Emperor Matthias, following the Defenestration of Prague in May of that year. However, the death of Matthias in March 1619 significantly accelerated and escalated the conflict.12

The primary reason for this escalation was the transition of power to Ferdinand II. Unlike his predecessor, who had occasionally shown a moderating influence, Ferdinand was an uncompromising proponent of the Counter-Reformation and refused to compromise with the Protestant estates.23

Following Matthias's death, the Bohemian directors refused to recognize Ferdinand as their legitimate king. In response to his hardline stance, the estates formally deposed him and elected Frederick V as the new king of Bohemia. This rejection of Ferdinand’s authority transformed the regional uprising into a broader struggle, as the conflict over the Bohemian crown drew in external powers and expanded into the Thirty Years’ War.13