But inspection of the Castle was not encouraged, and tourists of foreign appearance who showed a disposition to take snapshots in the vicinity were promptly checked in their pursuit of the pleasing but too common art of photography. Yet it was certain that, pigeon-holed in every war department, of continental and, perhaps, of certain Eastern powers, there were full details, or nearly full, of the elaborate defence works with which Dover was provided. It was known that Castle Hill was honeycombed with subterranean passages and galleries, and that the Castle (nowadays a barrack rather than a fortress) was thus connected with the modern forts in its immediate vicinity. Fort Burgoyne, to the north of the castle itself, was, until recent times, the strongest link in the chain of defence, its guns being of great calibre, and commanding a vast range over land and sea. But far more powerful, and better equipped with modern armament and military resources, was Fort Warden; such being the name given to the works which had been specially constructed as a safeguard against possible attack by means of the Channel Tunnel. The very hill had been hewn and carved and moulded to meet the needs of such a danger. Commanding the gradual sweep by which the railway descended towards the Tunnel, the great guns of Fort Warden were always trained upon the gaping archway from which the incoming trains were constantly emerging. The highest battery of the Fort occupied a dominating position overlooking all the _enceinte_ fortifications, which were armed with machine guns and small cannon. There was a subterranean passage connecting the fort with the waterworks of a large service reservoir in a hollow of the hill, which had been constructed in modern times to ensure an adequate supply of water for the troops and the Duke of York's School. Fort Warden was complete in itself; but, linked up with the other fortifications, it formed, as it were, the citadel of a composite fortress where, in the event of attack, the last stand would be made by England's defenders. Round the fort extended a double row of trenches, and within these was a moat. Strong wire entanglements defended the trenches, and the loopholes in the breastworks were protected by 3/4-inch steel plates with a cross-shaped opening for the rifles. In addition, strong bomb-proofs were provided for the reserves, with wide bomb-proof passages leading to certain of the other forts. In all directions on the hill were placed howitzers and mortars, most of the battery positions and gun epaulements being ingeniously masked and difficult for an advancing enemy to locate. The military scientist who had designed most of the elaborate defences and put finishing touches to those of earlier construction was Major Edgar Wardlaw of the Royal Engineers. His old friend General Hartwell held that from the point of view of an invading enemy, this quiet, unassuming officer was the most dangerous man in all the British army.