[fsloth]

Not only that but sometimes the works that have been preserved the best are obvious political tools. E.g. Julius Cesar's "The Gallic war".

Which, since we are on the topic, I absolutely must suggest as a reading for anyone who has the slightest interest in historical fact - or fiction - for that matter. Yes, the work is political boast about the campaign - but it is filled with juicy details on roman logistics, political action in the region, and so on.