If we cannot hinder vessels from entering our harbours, we should turn our attention to the putting it out of their power to lie, or come to, before a town to injure it. two means of doing this may be adopted in aid of each other. 1. heavy cannon on travelling carriages, which may be moved to any point on the bank or beach most convenient for dislodging the vessel …
2. heavy cannon on floating batteries or boats, which may be so stationed as to prevent a vessel entering the harbor, or force her after entering to depart.
Thomas Jefferson to Joseph H. Nicholson, January 29, 1805
Patrick Lee’s Explanation
How does a leader get a better result for far less money?
America’s 15 harbor cities were relatively defenseless against invading ships. Building forts, the conventional wisdom, would cost $50 million plus the cost of 12,000 soldiers to staff them in peacetime, 50,000 during war. Even so, there was general consensus the plan would not work. The fortifications might discourage or delay enemy ships but could not prevent them from entering our harbors.
Instead, the President proposed to the Maryland Congressman a system of moveable heavy canons, some on carriages, some on barges or boats. These would not keep ships out of the harbors but would prevent them from getting close to the cities within those harbors.
Fifteen U.S. harbors would require 240 gunboats, costing $1 million, and take 10 years to fully deploy. In peacetime, most could be kept in dry dock at minimal expense. Some would be deployed but lightly manned and near ready for action for $2,000/year each. A few would be fully manned and ready for defense for $8,000/year.
Far better, Thomas Jefferson proposed, to have an economical system that would work than an impressive and expensive system that would not.