William Schouler, A history of Massachusetts in the Civil War: Volume 1

The United States were already employing, to the full extent of their capacity, all the establishments in the country prepared or willing to undertake the manufacture of large ordnance; and were ready to give further contracts to any new parties who would take them. The special machinery and plans required for the casting and finishing of guns of large calibre are, however, so costly, the skill and experience necessary to their successful production so peculiar, and the risk so great, that new establishments built for this express purpose might, upon the cessation of the demand consequent upon a return of peace, be left unemployed, that the number of new parties who had come forward to engage in this manufacture was only three or four; and of these some had become already discouraged by the difficulties they encountered. The Ordnance Bureau, therefore, was of opinion that no expenditure which Massachusetts could make, would increase or expedite this production. The great scarcity of skilled mechanics, and the full and profitable employment given to all founderies and machine-shops in work attended with much less risk, added greatly to the difficulty.

At this moment occurred the celebrated encounter between the ‘Merrimack’ and the ‘Monitor,’ disturbing all further theories of naval attack and coast defence, and casting doubt upon the stability of the existing projects for the fortification and armament of our harbors, and demonstrating the absolute necessity of more powerful guns, and in much greater numbers than contemplated in General Totten's recent report. Indeed, in the night after the first irresistible attack of the ‘Merrimack’ on our fleet at Newport News, and in Hampton Roads, when it was thought that the rebel iron-clad might next day complete the destruction of the fleet, and, proceeding to sea, attack any of our most important seaports, the Governor received official advice from Washington to proceed at once to close the harbor of Boston by sinking temporary obstructions in the entrance to the harbor, so little could our defences be relied upon to repel an attack of this new and fearful engine.

The War Department immediately afterwards requested the