1. Managing to evacuate from Dunkirk. 26th May- 3rd June 1940. British and a small but sizable force of French troops survive the conquest of France, and are able to fight another day.
2. Winning of the Battle of Britain. Or if you like the dropping of all serious plans for invasion of Britain in favour for Russia. Ended 31st October 1940. Maintained a safe base in Western Europe allowing any re-conquest of Europe to happen.
3. Pearl Harbour. Brought the American war machine into the works, boosting the Allies manpower, natural resources and military capability in all fronts. Dec 7th 1941
4. Midway. America seizes the initiative in the Pacific. The Japanese fleet seizes to be a match winner, and makes victory for the Allies in the East a definite reality. 4th -7th June 1942
5. Battle of El Alamein. War in Africa shifts against the Germans. Sends into huge retreat and eventually wins the Allies most of the Mediterranean. 23rd Oct- 4 Nov 1942
6. The winning of Stalingrad. Turned the whole tide against the Germans. Date is for the counter attack aka Operation Uranus that trigged the shift in fortunes. 19th-23rd Nov 1942
7. The overcoming of the U boats. Mid 1943
8. Kursk. German counter in Russia decisively defeated. Soviet advance into Europe now guaranteed. Summer of 1943.
9. D-Day and Normandy. June 1944. Germans now fighting on three fronts.
10. Atom Bombs on Japan. Japan surrenders. 6-9 August 1945