The German 1942 offensive in the USSR began well, so well that Hitler split the offensive into two parts. The German Army was advancing on Stalingrad and threatening to cut Russia off from its oil fields in the Caucasus.
The US military went into the war just itching to invade France and take on the Germans ASAP. It was up to the British to talk them down, though the Allies did attempt a raid on the French coast at the port of Dieppe. Meanwhile, German intelligence infiltrated saboteurs into the United States.
The war against Japan brought the Nationalists and the Communists back into a new alliance, but it didn't last. Mao Zedong polished up his political writings and asserted his authority over the Party.
Adolf Hitler redeployed Luftwaffe units from the Eastern front to the Mediterranean. With Axis air superiority in the region established, shipments of equipment and supplies to Panzer Army Africa substantially increased. Soon Rommel was on the move again, this time driving the British deep into Egypt.
Rommel was surprised by a British offensive (Operation Crusader) and his forces were driven all the way back to where he had started from a year earlier. But in a few months, he and his army pushed the British back to where they had started.
When the United States entered the war, the German U-boats suddenly had many more targets.
Reinhard Heydrich was one of the most vicious of the Nazis. So much so that the Czechoslovak and British governments decided that he needed to be eliminated.
The Japanese execute their attempted ambush at Midway, and it fails catastrophically.
The US Navy sent two of its carriers into the southwest Pacific to thwart the Japanese campaign to take New Caledonia and isolate Australia. The Japanese responded by sending two of their own. The carriers engaged each other in the Battle of the Coral Sea.
Shortly after the Pearl Harbor attack, President Roosevelt asked the military to find a way to strike back at the Japanese Home Islands. It took an unorthodox approach to make this possible.