Complex sentence: Le Bel had written his chronicle for Jean, lord of Beaumont, uncle of Philippa of Hainault, who had been a supporter of Queen Isabella and the rebellion which led to the deposition of Edward II in 1326.
Split into simpler sentences: Le Bel had written his chronicle for Jean, lord of Beaumont, uncle of Philippa of Hainault. Jean had been a supporter of Queen Isabella and the rebellion which led to the deposition of Edward II in 1326.