Task Force 18 and Task Force 16 at sea

Task Force 18 left San Fransisco @ 2 April 1942 and consisted of the following ships:

As the USS Hornet embarked from San Francisco Bay, three messages were sent from Washington. From Arnold, "May good luck and success be with you and each member of your command on the mission you are about to undertake." From Marshall, "As you embark on your expedition please give each member of your command my deepest appreciation for their service and complete confidence in their ability and courage under your leadership to strike a mighty blow. You will be constantly on my mind and may the good Lord watch over you." And from Admiral King, "I hope and expect that the first blow operation of the Hornet will be a success. I am confident that it will be in so far as her officers and crew under your able leadership can make it so. Good luck and good hunting."

Task 18 Force was under command of Captain Marc Mitscher also Captain of the aircraft carrier USS Hornet.

Task Force 16 left Pearl Harbor @ 8 April 1942 and consisted of the following ships:

Task Force 16 was under command of Vice Admiral William Halsey also Captain of the USS Enerprise.

Task Force Eighteen became part of Task Force Sixteen on 13 April 1942 when both Task Forces met at sea. Commander of the newly formed Task Force 16 was Vice Admiral Halsey.

The flagship was the USS Enerprise (CV-6) -  Captain George D. Murray 

Also two submarines were involved : USS Tresher and the USS Trout. The USS Thresher departed 23 March 1942 for a patrol area near the Japanese home islands. There, she was to gather weather data off Honshū for use by Admiral William Halsey's task force (the carriers USS Enterprice and USS Hornet), then approaching Japan. +10.000 sailors making part of this Tas Force.

Important to repeat :

What was not discussed with Doolittle, but was understood by all, was the tremendous risk that the Navy was taking with this mission. If marauding Japanese submarines discovered the 16 ships force (Task Force 16 merged with Task Force 18 and became Task Force 16 commanded by Vice Admiral Halsey) steaming west, it would gain unprecedented opportunity to cripple what was left of the U.S. Navy's strength in the Pacific. Coupled with Japanese attack by long base bombers or heavy aircraft carrier force, it would mean the end of American Naval strength in the Pacific for months to come.

Pictures of Vice Admiral William "Bull" Halsey below.