Complex sentence: The death of Maria Theresa on 29 November 1780 left Joseph free to pursue his own policy, and he immediately directed his government on a new course, attempting to realize his ideal of enlightened despotism acting on a definite system for the good of all.
Split into simpler sentences: The death of Maria Theresa on 29 November 1780 left Joseph free. He proceeded to attempt to realize his ideal of enlightened despotism acting on a definite system for the good of all.