Complex sentence: His political career accelerated: in 1919 he went on to found the Fascio Italiani di Combattimento, which became the National Fascist Party in 1921; in the latter year he was also elected in the Chamber of Deputies.
Split into simpler sentences: His political career accelerated: in 1919 he went on to found the Fascio Italiani di Combattimento, which became the National Fascist Party in 1921. In 1921 he was also elected in the Chamber of Deputies.