Complex sentence: In 1196, Richard again nominated Arthur as his heir-apparent and summoned him, as well as his mother Constance, to Normandy, but Ranulf de Blondeville, 6th Earl of Chester, stepfather of Arthur, abducted Constance.
Split into simpler sentences: In 1196, Richard again nominated Arthur as his heir-apparent and summoned him, as well as his mother Constance, to Normandy. But right then, Ranulf de Blondeville, 6th Earl of Chester, stepfather of Arthur, abducted Constance.