Dr Adrian Goldsworthy

These are the communities you need to come over to you.

They're the ones that have been persuaded to join the Persian Empire.

But the Persian Empire works by allowing people to run their own affairs and just making it clear, you better be our friend because you don't want to be our enemy.

Alexander's doing the same thing.

None of these people have any particular feeling of loyalty to the Persians for any other reason, other than they're a dynasty that have done well.

If they can do well under Alexander, then... So it's a combination of it's the way the ground forces you to move, but it also makes sense.

And it's then tied in with what we were talking about earlier.

You want to deprive the...

Persian-run fleet of its bases and win the war at sea on land.

So it all comes together and makes sense for this to work.

It's the idea to father children.

To produce the next generation of soldiers.

Then you can come back and risk your life.

Well, they probably...

Or maybe not knowing that.

They don't know that.

Because the way Philip's wars have been fought is you go off, you fight for a lot of the year, but you always come home.

And it's been practical because it's never been that far.

This is the last time, really, that's practical.

And from then on, but they don't know.