World War II

World War II was a major conflict that took place from 1939 to 1945. Apart from a handful of neutral countries, it involved the whole of the Earth. In just about all appearances in the revived series, world war 2 was an unintentional visit by The Doctor.

History
One of the earliest steps on the road to war was taken in 1938 when the Nemesis statue passed over Earth. It caused Adolf Hitler to annex the country of Austria. (DW: Silver Nemesis) The war formally began on 1 September 1939 with the German invasion of Poland. (NA: Timewyrm: Exodus)

The immortal Jack Harkness served in the war as an RAF pilot (DW: Utopia); Fey Truscott-Sade served as a British spy and special operative in occupied Europe (DWM: Me and My Shadow); and Toshiko Sato's grand-parents and Rachel Jensen worked as code-breakers at Bletchley Park, alongside Alan Turing. (TW: Greeks Bearing Gifts) (MA: Who Killed Kennedy)

The Seventh Doctor ensured Hitler would fail to prevent the British evacuation of Dunkirk, making it possible for Britain to remain in the war. (NA: Timewyrm: Exodus)

In 1940 and 1941, Germany bombed Great Britain, an event known as the London Blitz. (DW: The Empty Child, et. al.) The Royal Air Force carried out its own systematic bombings of Germany. (EDA: The Turing Test)

During this period, Edwin Bracewell approached a desperate Winston Churchill, offering what to all appearances were robotic war machines of a futuristic design that Churchill could use first to fend off Luftwaffe air raids on London and later, in numbers, take the war to Germany. Churchill summoned The Eleventh Doctor and Amy Pond to view the new weapon. (DW: The Beast Below) The Doctor realised immediately that the "Ironsides" Bracewell had "created" were actually the Daleks. They were using themselves as bait to get the Doctor to aid in the recreation of the Dalek race. A small number of Spitfire fighters were briefly upgraded with Dalek technology to fight a Dalek saucer, but all alien tech was subsequently removed by the Doctor to prevent wide-scale tampering with history. The Daleks attempted to destroy Earth with a powerful explosive within Edwin Bracewell, who was actually an android of their construction. The Doctor and Amy defused it. The Daleks escaped and Bracewell presumably lived a normal, human life. (DW:Victory of the Daleks) Later that year, Churchill tried to telephone the Doctor, but instead reached River Song in Stormcage. He told her of a mysterious van Gogh painting he and Bracewell had found. (DW: The Pandorica Opens)

From 1940 to 1945, the Channel Islands were occupied by German forces. (NA: Just War)

In 1941, the Ninth Doctor and Rose Tyler landed in London during the blitz. While there, they defeated the Empty Child Plague and met Jack Harkness. (DW: The Empty Child/The Doctor Dances)

For a short time on both sides, the Cardiff rift linked 1941 and 2008, allowing Jack Harkness and Toshiko Sato of Torchwood 3 to meet with the original Captain Jack Harkness and to cause suspicions in the members of the institute about Bilis Manger. (TW: Captain Jack Harkness)

In January 1941, Nazis in France forced Pierre Vedrun to build them a machine to travel to England. His daughter, Monique Vedrun used it to escape, but actually also traveled through time to the 1970s. There, the Third Doctor met the Nazi's and her, secretly following them back to 1942. He attempted to stop the Nazi from becoming knowledgeable time travelers, tricking them to going through it again, but this time to a British jail in 1942. (TVA: Timebenders)

In June 1941, a small group of Germans, assisted by Miss Wyckham, entered the south coast of England, using a piece of Chronosteel found in the Rhineland to block early warning systems and allow the Germans to invade Great Britain in full force. Clyde Langer, and George Woods stopped this, with Clyde returning the Chronosteel to its rightful place with the Shopkeeper and Captain in 2010. (SJA: Lost in Time)

In 1943, Fenric was working with his Haemovores at Maiden's Point. Russia and Britain, while nominally allies, were plotting against each other in preparation for post-war conflicts. (DW: The Curse of Fenric)

In June 1944, the allied troops staged the Normandy landings to invade mainland Europe. (EDA: The Taint)

During the same year, the Seventh Doctor and Ace arrived at Colditz. (BFA: Colditz)

In 1945, an amnesiac Eighth Doctor, Alan Turing and Graham Greene were involved in an unexplained alien conflict and survived the Dresden firebombing. (EDA: The Turing Test)

The Eleventh Doctor was in a German prisoner of war camp and tried to escape. (DW: The Impossible Astronaut)

Alternate timeline
In a timeline in which the Doctor did not find the Ironsides, they turned the tide of the war and took the fight to Germany. After the war was won, Churchill was pressured by Stalin and Truman into having the Ironsides destroyed by a nuclear bomb. (DWAN: Doctor Who The Official Annual 2011)