Complex sentence: Meanwhile, the Prince of Wales has been scheming to have himself made Prince Regent-at which point he will effectively be King-and allies with the opposition-lead by Charles Fox-to Prime Minister William Pitt's increasingly unpopular government.
Split into simpler sentences: Meanwhile, the Prince of Wales has been scheming to have himself made Prince Regent, at which point he will effectively be King. He allies with the opposition, led by Charles Fox, to Prime Minister William Pitt's increasingly unpopular government.