Complex sentence: As a composer he represented the school of Franco-Flemish polyphony in Bohemia, but his activities as a Protestant and a Czech nationalist resulted in his execution by Catholic forces after the Battle of White Mountain during the Thirty Years War.
Split into simpler sentences: As a composer he represented the school of Franco-Flemish polyphony in Bohemia. His activity in revolt of Protestants resulted in his execution by Catholic forces after the Battle of White Mountain during the Thirty Years War.