Dominic Sandbrook

And he has been looking particularly at somewhere you've already mentioned, Tom, which is the Ottoman capital, Constantinople, that basically all the great powers have been eyeing very hungrily.

Well, it's not clear what will happen to Constantinople in Churchill's plan after the war.

So it's not actually clear that the Russians will get it.

But the reason that it is so coveted is that Constantinople commands the narrow straits that divides Europe from Asia.

But also this is the straits that divides the Black Sea from the Mediterranean.

So the reason it's so important to the Russians is that this is their warm water state.

sea route out of the Russian Empire into the seas of the world.

And this strait, this waterway, basically the waterway that goes from the Sea of Marmara, outside Constantinople, south to the Aegean in the beginning of the Mediterranean, this strait is called the Dardanelles.

Now, to give people a sense,

The Dardanelles are 38 miles long, but very narrow, no more than four miles wide at their widest point.

So you can imagine almost like a canal, I guess.

Now on the right-hand side, as you look at the map, the southeastern side, the Asian side, is the coast of Anatolia, of Asia Minor, specifically the city of Chanakali.

And on the left side, as you look at the map, the northwestern, the European side, that's made up of a long, narrow peninsula, which is named after one of the towns on the peninsula, which is the town of Gallipoli.

So that is the Thracian Chersonese, as was.

So Churchill has been long obsessed with this strait.

So just a few weeks into the war, he had said, why don't we send a British and French fleet north through the straits?

And then if necessary, if we came to war with the Ottomans, war with Turkey, we could bombard and occupy Constantinople itself.

And his argument for doing this is, if it works, and that's a big if, this could be a game changer in the war.

Why?

Number one, if we held Constantinople in the Straits, we'd have a warm water sea route so that we, Britain and France, could supply Russia.