Complex sentence: With their leader gone, the peasant army's morale plummeted, their line shaking apart and allowing a cavalry charge to tear through their centre, causing them to break into a shapeless mass. This mass was then systematically exterminated, the charge led by Charles of Navarre.
Split into simpler sentences: With their leader gone, the peasant army's morale plummeted and their line fell apart, allowing a cavalry charge to break through their centre. This caused the peasants to break into a shapeless mass. This mass was then systematically exterminated, the charge led by Charles of Navarre.