Complex sentence: As Wallace charges toward the departing Longshanks on horseback, he is intercepted by one of the king's lancers, who turns out to be Robert the Bruce, but filled with remorse, Bruce gets Wallace to safety before the English can capture him.
Split into simpler sentences: As Wallace charges toward the departing Longshanks on horseback, he is intercepted by one of the king's lancers, who turns out to be Robert the Bruce. Remorseful, he gets Wallace to safety before the English can capture him.