[Sawdring]

I have the Art of War but haven't read it yet. I have heard he borrows a bit from Vegetius in his Art of War but without reading it I'm not sure.

[PsyOp]

I think you're right. Much of it is based on conversations he had with a prominent Italian military figure of his time (I forget which one) as well as some other associates of his. I don't think he had any first hand military experience.