John G. Barnard to Edwin M. Stanton, October 13, 1863

Hon. E. M. Stanton, Secretary of War:

Sir: All the officers to whom the Government has committed the defense of harbors, from General Totten, Chief Engineer, down to his lowest subordinate, and all those who represent the interests of cities to be defended or the civil power of these municipalities or States, are unanimous as to the necessity of providing obstructions in channels to be defended, to arrest and detain iron-clad vessels under the fire of the shore batteries.

For the last six months or more the matter has been undergoin investigation in New York, but as yet, no practical result has flowe from it, and in the case of engineer officers, while all lay down the necessity of the thing, none can answer what it shall be. That the

roblem is one of exceeding difficulty all admit, but if nothing is

ecided as to plan even, what shall we do when the time for its use arrives ?

The collection of materials alone is an immense undertaking; the fabric must be the result of time. I have devoted some thought to the matter, and have had the assistance of very able engineer officers to sketch out a project of obstructions. I believe the only way to solve the problem is to go at it practically.

An efficient barrier in the Potomac at Rozier’s is estimated at about $300,000. If we should get into a war with a maritime power while the rebellion is yet powerful, Washington is, next to New York, a probable point for attack through the Potomac. It has now no formidable batteries, as New York and Boston have. The guns which will be mounted in the two new earth-works (sixteen in all) appear to be the only thing likely, for a long time, to oppose an enemy’s reaching Washington through the Potomac. Should the emergency occur, therefore, the engineers and the navy would both be called on to make their opposition efficient by providing the only thing that can do so, viz, obstructions.

But Washington has no such command of resources and material as New York, Philadelphia, and Boston have. Its navy-yard would not be able to furnish the immense amount of cables required ; the timber or hulks in such kind and quality as required for such an obstruction are not to be had. Hence, the necessity of a provision beforehand. But, independently of the importance of such an obstruction beforehand, it is particularly important that something should be done at once to solve this problem, and there is no better place for the experiment than here. When the thing has once been done we shall know what to do in all such cases. The importance of obstructions has been fully proved at Charleston Harbor, if we ae believe that it is they which have paralyzed our fleet of ironclads.

In view of the above statements, I suggest that an appropriation be asked of Congress of $300,000 ”for providing obstructions to be moored in the Potomac, to render the shore batteries more efficient for the protection of Washington against maritime attack,” and I further request that the Secretary of War authorize a sum of $150,000 from the appropriation for ”Contingencies of fortifications,” or any available source, to be immediately applied to a partial construction of such obstructions, and in order to arrive speedily at some practical conclusions as to what they shall do.

very respectfully, your most obedient servant,