Complex sentence: With Phocas facing two separate military fronts, the emperor would be unable to concentrate the majority of his troops on either one of them, encouraging Heraclius of his chances to succeed in this confrontation.
Split into simpler sentences: With Phocas facing two seperate military fronts, the emperor would be unable to concentrate the majority of his troops on either one of them. Encouraging Heraclius of his chances to succeed in this confrontation.