FDR Library
President's Secretary File (PSF)
Box 59
Folder: Navy – January-June 1941

THE WHITE HOUSE
WASHINGTON

January 7, 1941.

MEMORANDUM FOR
            THE PRESIDENT

The attached represents the best estimate yet possible of the projected strategic and tactical employment of MTB's.

Respectfully,
/S/
D.J. CALLAGHAN

In Reply Refer to Initials and No.

Op-22-1
(SC)A16-3(5)

NAVY DEPARTMENT
OFFICE OF THE CHIEF OF NAVAL OPERATIONS
WASHINGTON

January 7, 1941

Confidential Memorandum for Captain Callaghan:

Subject: Strategic and Tactical Employment of P.T. Boats.

1. The outstanding characteristics of those boats are

(a) High Speed (40-45 kts)
(b) Small size (77-81 feet)
(c) Maneuverability
(d) A powerful torpedo battery (4 – 21" torpedoes)
(e) Very weak gun battery (4 – .50 caliber M.G's.)
(f) No sound equipment.
(g) No depth charges.
(h) Very limited smoke making capacity.

2. These boats are a serious menace to large combatant surface vessels (BB's, CV's, CA's, CL's), in relatively smooth water, at night, and under conditions of reduced visibility by day. They should be effective against merchant vessels in both good and in reduced visibility. For attacks against large combatant ships, during good visibility by day, the P.T. Boats appear to be much less effective than bombing or torpedo planes. The P.T. Boats armed as indicated in paragraph 1, are ineffective against submarines.

3. They are weapons of opportunity and should find their most frequent opportunities in restricted waters. The waters of the Adriatic and those about the Dodecanese Islands are especially favorable for their employment. The English Channel is also a very favorable theater for these boats when weather permits.

4. In the continental United States, in the West Indies, and in the South Pacific it would appear that these boats would, as a part of the local defense forces, serve as a deterrent to raids by surface ships, and to a lesser extent, as a deterrent to raids by aircraft carriers. They would probably have few opportunities for actual attacks, but their existence would reduce the probability of the use of enemy surface vessels within the radius of operation of the P.T. boats.

5. In the Far East, the P.T. boats, or preferably a modified and more rugged type, operating from bases in the Philippines, the Mandates, and the East Indies, could be very effective in blocking enemy trade routes. Because of their light construction and their weak antiaircraft battery, however, they could not be expected to operate successfully during daylight in the presence of enemy aircraft.

6. Generally, therefore, it would appear that P.T. boats could be most usefully employed in locations where it is impracticable for us to maintain strong forces of combatant surface ships and/or aircraft. The maintenance of the P.T. boats in these locations, however, requires rather extensive provisions for upkeep and repair. British experience indicates that the work of upkeep and overhaul of the engines of P.T. boats is comparable to that for airplane engines. Provision must also be made for hauling or hoisting the P.T. boats out of the water at frequent intervals to clear them of marine growth.

7. In attack, it is expected that the P.T. boats will operate in sections, or tactical units, of not more than three boats each, although several of such tactical units may be employed in a loosely coordinated attack. These attacks should be pushed home to ranges not exceeding 1500 yards, depending upon surprise, high speed, and maneuver, to permit torpedoes being launched before an effective fire can be brought against the P.T. boats. In a coordinated attack by several sections, the section attacks should be made from as widely differing directions as is practicable. For safety in retirement, after an attack, the P.T. boats must depend on speed, maneuverability, and on the use of smoke if available.

8. In the present war, the successful use of the P.T. boats has been largely confined to night raids of Channel convoys by the Germans and to reconnaissance and chance attacks on supply ships by the British. The Italians have had comparatively little success in the use of these fast torpedo boats, but this is not necessarily the fault of the type.

9- At present the precise tactics to be used in attacks under different circumstances are being investigated by Lieutenant Caldwell, who is in command of our P.T. boats. He is a very capable and enthusiastic young officer and he has been given a free hand by Operations to work out his own ideas.

/S/
W. A. LEE, JR.