Raid That Avenged Pearl Harbor (2015)
In response, FDR (57 years old in 1941) ordered the U.S. Pacific Fleet moved from California to Pearl Harbor, over the fierce objections from high-ranking admirals. In July 1941 Japan invaded southern French Indochina, which was a clear signal that next on the list would be Hong Kong, Singapore, and the oil-rich Dutch East Indies. FDR stopped US gasoline shipments to Japan, which took away 80% of Japan's oil imports. FDR also ordered Japan's assets in the U.S. frozen.
Japan also attacked Guam, the Phillipines, Wake Island, Hong Kong, and Midway. FDR, who loved the Navy (he was a former Ass't SecNav as was TR) just couldn't get his mind around why US ships were nothing more than sitting ducks for the Japanese at Pearl Harbor. Half of America listened to FDR give his 518 word Pearl Harbor speech on 8 December 1941; it was the largest daytime audience for a radio broadcast in US History, with 62 million listeners.
Guam had soon fallen after Pearl was attacked, as had Wake Island. U.S. airpower in the Philippines was wiped out and Japan would soon take Manila. FDR understood that continued defeats would demoralize the US public. 50% of Americans believed that Japan would bomb U.S. cities; victory on the battlefields/sea was the way to allay public fears and improve morale so the unity after Pearl Harbor could be sustained (and that blame for Pearl would be lost in the rush of Patriotism). Many, many Americans were beyond-upset that the US Navy had been asleep at-the-switch at Pearl Harbor
Admiral Ernest King, the Commander-in-Chief of the US Fleet, badly wanted to take any kind of offensive against Japan, and by 10 January 1942, the normally-agitated King was even more agitated/worked-up than usual with the continuous string of bad news coming from the Pacific. While the official plan was to be on the defensive in the Pacific while fighting in Europe, King wanted to take any opportunity to go at Japan in order to keep them off-guard, and perhaps to forestall or delay future attacks on strategic U.S. possessions in the Pacific.
Duncan was already thinking about landing planes on airfields in China, and also he would need bombers that could fly from outside the 300 mile range of Japan's patrol flights, strike Tokyo, and fly to China. Duncan viewed the B-25 (the Mitchell) as the best-suited for the mission, since it could handle the range, and also carry a heavy payload of bombs. As far as the carrier, Duncan had the USS Hornet in mind. The Hornet was a new carrier being readied for action in Virginia, and it could be ready in the Pacific at about the time (he figured) the bomber side of the plan was ready.
"Hap" Arnold was on board, Duncan would be in charge of the Navy side of the operation.
On 21 December 1941, Arnold was ordered by FDR to find a way to bomb Japan, but Arnold had no clear idea how to accomplish that order. Adding to Arnold's travails was that only 79 of 231 planes in the Pacific were still in action after Pearl Harbor. And demand for US Army Air Corps planes far exceeded supply. On 4 January 1942, Arnold was part of a conference over North Africa with Admiral King. King suggested to Arnold the idea of using US Army bombers from carriers. The idea piqued Arnold's curiosity, and Arnold instructed his staff to immediately start examining the idea.
By mid-January 1942, Low and Duncan appeared in Arnold's office and suggested B-25's instead of retrofitting cargo planes. Using B-25's would mean that two carriers wouldn't have to be nearly as close to Japan, and since the B-25's would be able to continue to China, the two carriers could turnaround and return home right after the B-25's took off.
Arnold then added another qualifier, in that the plane's wingspan couldn't exceed 75 feet. Doolittle told Arnold that the B-25 was the only option. Arnold was on the phone to King, and the plan was a go. The USS Hornet would depart the West Coast on-or-around 1 April 1942, and on that date the USS Hornet should be finished in Virginia, and en route to California via the Panama Canal.
Duncan would oversee the trial takeoffs of the B-25's from the Hornet as well as organizing a naval task force in Pearl Harbor. Arnold would need to select someone to modify the B-25's and to train the aircrews . . . Doolittle was the man, and Arnold told Doolittle to let him know if anyone "got in his way" with the plans for the mission.