Dr Adrian Goldsworthy

He is going to need local cities to give him food, particularly when the campaigning season ends and it comes into the winter to survive over that.

So he needs communities to join him, which means he's got to frighten them, but also persuade them it's worth their while.

So if your great king is telling you we'll burn everything and you'll make it somehow through the winter, don't worry about it too much.

then you might think, well, we're better off with Alexander.

And once he's won that battle, so again, there is some strategic sense in this.

And again, we know it's Alexander and you don't want to fight Alexander.

But the logic is actually protect their lands, meet the Macedonians early on and beat them.

But with Memnon saying, again, he gets credit because he's a Greek.

He's a Greek in the Persian camp, and he tends to get a good press.

It's a little bit like with Napoleon's marshals, Marshall MacDonald, because of the Scottish ancestry.

He tends, in Anglophone sources, to get quite a good write-up, rather more than perhaps is deserved, just because we like it.

It's one of ours.

There is that sort of intrinsic sense that, oh, yeah, we're best at everything.

It would make sense, but it's a very difficult thing to impose on anybody, to get them to destroy their own crops, because you will suffer as the local community.

And again, this is something you're going to have to be making your decisions on on the spot.

You can't consult with the great king.

It takes too long.

So they begin to do it after Granicus, largely because they haven't got a field army anymore.

So they can't oppose him in the field.

So it comes down to, let's hold as many strongholds, as many cities as we can, and let's try and deprive him of food.