A US Naval Task Force is a large group of ships operating togother. In World War II it could have been 1 or 2 Battleships 1 or 2 or 3 Aircraft Carriers 2 or 3 Crusers, bunch of Destroyers and other Escort ships.
Here is a report on a Japanese Task Force. It would be the same more or less for any country.
November 26, 1941.
Memorandum for the Chief of Staff:
Subject: Japanese Naval Task Force.
The following information was received from the Commandant 14th Naval District through the Office of Naval Intelligence at 12: 45 a. m., this date:
1. The Japanese have been organizing a naval task force for the past month comprising:
a. Second Fleet: Under the command of Commander-in-Chief, Second Fleet. (The Second Fleet corresponds roughly to our Scouting Force, consisting mainly of strong Cruiser Divisions).
b. Third Fleet which formerly was the China Coast Command Force including its first and second base forces, constituted by miscellaneous small vessels.
c. Combined Air Force consisting of all large carrier forces.
d. Also destroyer squadron 3, air squadron 7, submarine squadron 5, and possibly 1 battleship division from First Fleet consisting of 3 battleships.
Summary of Above: 14 Heavy Cruisers, 4 Light Cruisers, 10 Carriers, 3 Light Cruisers. 2 Destroyer Squadrons (24 destroyers), 2 Submarine Squadrons (18 submarines), and possibly 3 battleships.
2. The combined air force has assembled in Takao, Formosa, with some units believed in Hainan Island. The Third Fleet is believed moving in direction of Takao and Bako, Pescadores off West Coast of Formosa, from home waters in Japan. Units from the Second Fleet are at present possibly enroute to South China as advance scouts. Strong concentration of submarines and air groups in the Marshalls. Present location other units of this task force are not known.
3. The evaluation put upon the above information by the Commandant, 14th Naval District is that a strong force may be preparing to operate in Southeastern Asia, while component parts thereof may be expected to operate from Palao and the Marshall Islands.
Brigadier General U. S. Army
Acting Assistant Chief of Staff, G-2.
Secretary of War
Assistant Chief of Staff, W. P. D.
I. B. File
Far East Section
(EXHIBITS OF THE JOINT COMMITTEE, PHA, PT. 14, EXHIBIT NO. 33 MILITARY INTELLIGENCE ESTIMATES PREPARED BY G-2, WAR DEPARTMENT)