Complex sentence: The closing narration explains that this was one of the first victories that the French had that would eventually lead to total victory, however, the rebellion was defeated by Royalist supporters of nine year old Henry III in 1217.
Split into simpler sentences: The closing narration explains that this was one of the first victories that the French had that would eventually lead to total victory. However, the rebellion was defeated by Royalist supporters of nine year old Henry III in 1217.