Complex sentence: Ideas of Ante Starčević, the leader of the Party of Rights between 1851 and 1896, confronted Croats with the neighboring nations, which included Serbs, and served as a basis for the destructive politics of his successor Josip Frank who caused numerous anti-Serbian incidents.
Split into simpler sentences: Ideas of Ante Starčević, the leader of the Party of Rights between 1851 and 1896, confronted Croats with the neighboring nations, which included Serbs. Starčević's ideas served as a basis for the destructive politics of his successor Josip Frank who caused numerous anti-Serbian incidents.