Complex sentence: Napoleon, who had been sick with a cold and was too far from the action to really observe what was going on, refused to send his subordinates reinforcements; he was hesitant to release his last reserve, the Imperial Guard, so far from France.
Split into simpler sentences: Napoleon, who had been sick with a cold and was too far from the action to really observe what was going on, refused to send his subordinates reinforcements. He was hesitant to release his last reserve, the Imperial Guard, so far from France.