“If an attack threatened Charlestown, submarines could proceed by rail from New York at thirty-five miles an hour, in certain safety.
“Delivery of such boats as I refer to could begin within nine months, and three or four a month could be delivered thereafter, using only existing facilities.
“We have plenty of shops which could turn out the gasoline engines they would need. Diesel oil engines are superior for a boat can be run twice as far on a given quantity at one-fifth the cost, and the heavy oil used in Diesel engines is non-explosive, but the disadvantages of gasoline could be largely overcome by carrying the fluid in tanks outside the boat. Thus a supply for 500 miles of cruising could be carried without danger.
“I believe this suggestion for the provision of amphibious submarines to be the most important suggestion for the defense of the United States which has been made in many years. It offers the quickest, the most effective, and the least expensive defense so far imaginable.
“Our capacity for turning out craft of this type would be enormous.
“All lake and ocean yards could build the hulls, all the automobile and boat engine building plants could build engines for them, and there are several electric appliance and storage battery plants that could build the electrical equipment.
“To my mind, the day is close at hand when the only safe place for a battleship will be an interned pond closely protected against land attack.
“And let us consider the cost of maintaining such a defensive fleet in time of peace, comparing it to the cost of the conventional modern naval fleet. To man a submarine of the coast defense type will require twenty men, while the amphibious submarines which I have suggested can be manned by crews of ten men each.
“Say we had fifty of the amphibious boats. That would require a total of 500 men. Estimate the force necessary to man the coast defense type at 3,000 men. Thus, less than 4,000 men would give us a perfect defense for every harbor in America, and, I think, could prevent any invading force from landing elsewhere on our shores.
“The system would be immensely superior to our present coast defense system, each fort or group of forts of which defends only a small radius of territory immediately adjacent thereto. This submarine defense, through its mobility, would defend not only our harbors, but every inch of our shore line.”