Magoo, don't take everything literally, just because the same voice actor was voicing narration and spoke in first person doesn't mean that everything spoken was part of that character. Not at all. Distinguish where narration goes and where not. Far fetching assumptions of what might have happened afterwards and nitpicking don't float the boat in my opinion, but that's just my own. It's a game, not life, we aren't talking about real world history here, but even so any history can have contradicting interpretations voicing opinions and drawing cause-effect conclusions that may at times negate each self out.
@Klaw117: yes. Four became legend. Fifth one, Hispania, was assumed to be lost, like the other three. However it wasn't, and from it came two pirate houses. There is no 800 years old general, just try to listen and understand where goes third person narrative and where it is spoken from the character itself. Because it happens to be the same voice actor it gets confusing at first. The fate of other there sleeper ships remain unknown. I suppose developers left them in the state of uncertainty to be used in sequel, a game which was intended to be but was never made. Seems most logical and typical method of leaving hooks in story for possible expansions/sequels.