One of the first things the USAAF did was cram as many B-25's as possible onto an aircraft carrier, overload them with fuel, and sail them across the hostile Pacific waters to launch a raid on Tokyo. The raid was conceived and led by Jimmy Doolittle, who, despite his name, did a LOT for aviation during and after the war, setting numerous land speed and distance records and pioneering modern instrument flying techniques. The raid ended badly, with the majority of the aircraft running short of fuel and crashing in China, but the effect on U.S. morale was significant, and it forced the Japanese to permanently station a group of fighters in Tokyo to defend against any further hare-brained stunts by those crazy Americans.
Down in the balmy Mediterranean, the RAF was busy beating up Rommel's supply lines, and turning Malta into one of the worst vacation spots of 1941. Well, actually, the Luftwaffe was doing all the work to put Malta on Club Med's ten-worst-places-to-get-a-tan list, but it was the stubborn attacks on German naval and air convoys by the pilots stationed there that were inviting all of the unwanted bomb craters. Rommel became famous for intimidating his opponents with dummy tanks made of cardboard because his real tanks were sitting at the bottom of the Mediterranean Sea, courtesy the RAF. Unfortunately for Rommel, his efforts served only to annoy the British and keep the map makers busy, but he achieved little lasting success. His chronic lack of supplies and the necessity of including the underachieving Italian forces into his plans doomed the Africa Korps to eventual extinction. Rommel also had little regard for close air support, which had thus far proven to be one of the keystones of the Wehrmacht's blitzkrieg, and his military efforts predictably suffered from his reluctance to utilize the Luftwaffe to its fullest potential. The Allies made no such mistake, and cannon-armed Hurricanes made life miserable for German tankers. (or, um, Panzerers)
In Russia, the winter snows were beginning to thaw, leaving a bruised and battered German army stuck in the mud again. The Luftwaffe had returned to the skies, however, and the Russian offensive petered out. Reinforcements began to arrive and the latest crop of German generals began to plot their summer offensive. The Luftwaffe began to receive a new fighter plane, too, the Focke-wulf Fw190, a heavily-armed and versatile aircraft that gave allied pilots fits. It was fast and sturdy and could roll faster than a dachshund falling down an alpine ski slope. It never completely replaced the 109, as its performance slacked off at high altitude, but it had many allied pilots clamoring for better planes. In response, the British re-engined their Spitfires to keep up, which worked out very well. The Americans had no immediate answer, but their new Lockheed P-38 Lightning was every bit as fast and twice as pretty. It only met with lackluster success in Europe, though, owing to its problematical high-altitude performance (a distressing lack of cabin heat made the cockpit a better place to keep TV dinners than pilots) and its tendency to reach compressibility in a high-speed dive.
Compressibility is an aerodynamic event that occurs as a plane approaches the speed of sound: the control surfaces simply stop working because of shock waves that disrupt the airflow over the wings and tail, making it impossible for a pilot to pull out of the dive, with predictably messy results. The Lightning was the first fighter to encounter this unfortunate phenomenon thanks to its high dive speed, and Lockheed had to wait until one lucky test pilot managed to survive the ordeal before they were able to figure out what was happening to their planes. Eventually, a dive brake was installed that solved the problem, but not before fighter pilots became wary of diving after German planes in the Lightning. The Lightning was much more popular in the Pacific, where the warm weather, long missions and lower fighting altitudes made it an ideal fighter. Pilots welcomed the extra engine on their routinely long flights over water, and the Japanese Zero pilots caught a disturbing glimpse of U.S. technical superiority. Despite its relatively small numbers and never ending maintenance headaches, the Lightning managed to knock down more Japanese planes than any other type of aircraft. And it was just a portent of things to come.