The War Begins reveals in detail the events of the early carrier raids by the U.S. Pacific Fleet against the Japanese in the first half of 1942 in the Pacific War. After the attack on Pearl Harbor, carrier airpower would take on the supreme offensive role against Japanese forces in the first phase of the war. America's fast carrier task forces, with their aircraft squadrons and powerful support warships, took on the challenge, but the Pacific Fleet carrier force had a total of three carriers in the Pacific on 7 December 1941. Adm. William F. Halsey's Task Force 8, positioned on the Enterprise, and Rear Adm. Frank Jack Fletcher's Task Force 17, on the Yorktown, executed the first raid on Japanese positions on 1 February 1942, with attacks on the Marshall and Gilbert Islands. Raids on Rabaul, Wake Island, and Marcus Island followed. The most daring carrier raid was the unorthodox Doolittle Raid on Japan itself, on 18 April, when sixteen U.S. Army B-25 medium bombers launched from the Hornet. Though the carrier raids had limited material effect on Japan's continuing advance in the Pacific, they yielded valuable operational experience for U.S. carrier forces, kept open the lines of communications to Australia, and boosted morale. The raid on Tokyo inspired the elaborate Japanese plan to occupy Midway Island in June, resulting in a major carrier battle and the U.S. Navy's greatest victory.