Complex sentence: The city played major roles in the Bohemian and Protestant Reformation, the Thirty Years' War and in 20th-century history as the capital of Czechoslovakia, during both World Wars and the post-war Communist era.
Split into simpler sentences: The city played major roles in the Bohemian and Protestant Reformation and the Thirty Years' War. In 20th century, the city was the capital of Czechoslovakia, during both World Wars and the post-war Communist era.