Its principal defences are the outer and inner castles of Europe and Asia, and the castles of Sestos and Abydos.

Constantinople stands about one hundred miles from its entrance into the Sea of Marmora, and at nearly the opposite extremity of this sea.

The defences of the channel had been allowed to go to decay; but few guns were mounted, and the forts were but partially garrisoned.

In Constantinople not a gun was mounted, and no preparations for defence were made; indeed, previous to the approach of the fleet, the Turks had not determined whether to side with the English or the French, and even then the French ambassador had the greatest difficulty in persuading them to resist the demands of Duckforth.
The British fleet consisted of six sail of the line, two frigates, two sloops, and several bomb-vessels, carrying eight hundred and eighteen guns, (besides those in the bomb-ships.) Admiral Duckforth sailed through the Dardanelles on the 19th of February, 1807, with little or no opposition.

This being a Turkish festival day, the soldiers of the scanty garrison were enjoying the festivities of the occasion, and none were left to serve the few guns of the forts which had been prepared for defence.