Complex sentence: Colonel Hackworth was being groomed for bigger and better things, but he had no desire to become a general officer and declined once again to go to the war college and would soon become totally fed up with the system, not to mention the war in Vietnam.
Split into simpler sentences: Colonel Hackworth was being groomed for bigger and better things, but he had no desire to become a general officer and declined once again to go to the War College. Hackworth soon became totally fed up with the system, not to mention the war in Vietnam.