17. There is a hazy kind of national prejudice against fortifying, and especially the metropolis. Yet this was done by the Romans in the middle ages, and even by the Parliamentarians in defence of liberty against despotism. In 1642 the very plan now suggested was followed by Cromwell. Forts were erected at the entrances to the city, and lines and entrenchments connected them together. The Common Council and other chief men of the city, with their wives and families, three thousand porters with their wives, and five thousand shoemakers, six thousand tailors, and five thousand sailors, all worked in the trenches at different days in May and June. “Oh, but we have our wooden walls!” Thank God, we have our wooden walls, and we trust them; but a fleet may be, as it has been, decoyed out of the Channel; indeed, it is possible that even an English fleet might meet with a temporary reverse; and in these days of steam, the time thus gained need not be more than an hour or two to enable the enemy to get the start of us. To an invading force, the fear of their retreat being cut off, and being severed from the base of their operations, would not be thought of. If London is worth attacking, it is worth running the risk of letting an army be left to its own resources, or even of being cut off altogether. Our fleet is a great protection, without doubt; but it does not, and cannot, give that perfect assurance against a sacking of London which is what we demand. The fleet is a right thing, but may not be always in the right place. 18. We must have a new and inner line of defence. “Well,” opponents will say, “we have our great fortresses of Portsmouth and Plymouth, which we are strengthening at this very time.” Portsmouth and Plymouth are most valuable, but not directly as defences of the capital: they are virtually important; but only as naval arsenals, as storehouses, refitting places, or _points d’affaires_ for our navy. No! we may have as many lines as we please, but for our last and great efficient line of defence we must come nearer home. The line, to be well manned, must be short. We must fortify the point that is most liable to attack. London itself must be our _Quadrilateral_. 19. The military argument that the construction of fortresses necessitates the locking up of a great part of our regular troops, was formerly, no doubt, a strong and valid objection; but it will no longer hold good: whatever hesitation we may have in trusting untried troops for the first time in the field, there can be no doubt that we may safely entrust to them the charge of our fortresses. This is a work, too, which the intelligence and readiness of resources that we are sure to find in troops raised from our middle classes, would render volunteers particularly fitted to perform.