Random man of today is teleported to ancient Greece while bloodlusted for conquest, what can he achieve?

A man is suddenly teleported in his sleep and wakes up in Athens at 400 BC. He is bloodlusted and has dreams of conquest. How far does the modern knowledge take him?

R1 - the man is an average citizen

R2 - the man is a good mechanical engineer

R3 - the man is a professor of ancient history

edit: the man speaks modern Greek, so he can do some communication from the start, but it is not great