In March 1942, the Allies were on the retreat everywhere. Most of the targets the Japanese high command had wanted were in their hands, or soon would be. The Americans began to realize that a bold stroke was needed to raise the morale of the public and of the fighting forces.
Most of occupied Europe had been under Nazi domination for at least two years. While there was no immediate threat of the Allies losing the war, the Allied command, especially the British, wanted to win a battle in order to raise morale at home and abroad.
In contrast, the morale of the Japanese couldn't be higher. Both the public and many servicemen thought the war was progressing well. It was inconceivable that anything could stop the Imperial forces. The arrogance of the west was shown in the superiority of the Japanese war technology, tactics, and in the individual fighting man. The Allies did not have the heart to fight.
Many Japanese Officers and civilians who had traveled to the United States, like Yamamoto, knew that it was a matter of time before the Allies struck back. And when the American industrial capacity reached full stride, then they would be able to field numerically superior forces. But no one in Japan doubted that the Japanese spirit would win the day; that the home islands would come under attack was not ever considered.
What they did not expect or even could predict was that plans were already underway to attack Japan itself within the month. In contrast to the interservice rivalry that plagued the Japanese throughout the war, the Americans could work together; if not in harmony, then in consensus. This consensus had married the long-range US Army B-25 Mitchell bomber to the US Navy carrier USS Hornet. An air racing hero, Lt. Col. James Doolittle, commanded the mission. The Hornet was a new ship, commissioned in October 1941. Its 800-foot flight deck was crammed with 16 of the twin-engined bombers, the last one's tail sticking out over the fantail. The USS Enterprise escorted to provide air cover.
The plan was simple, yet against the limits of all theory: fly a land-based bomber off of a carrier deck, bomb Japan, and fly to China to support operations there. The bombers could not obliterate a target, but that wasn't the point. The Japanese pride would be deflated, the fight would be brought to the Home Islands.