The series's initial point of divergence occurs when Spanish Nationalist leader José Sanjurjo avoids the plane crash that took his life in reality.
A second divergence occurs when British and French appeasement at the Munich Conference leads Adolf Hitler to decide that he should attack while his opponents are unprepared; he gets his casus belli when Konrad Henlein is assassinated by a fictional Czech nationalist.
After an initial tenacious resistance to the German army, subsequent Polish and Hungarian invasions combined with a Slovak rebellion lead to Czechoslovakia's collapse.
Moreover, in this history the Skoda factory was destroyed during the fierce Czech resistance, rather than falling intact into German hands and starting to produce high-quality tanks for them.
The final result is that the German Blitzkrieg is not as devastating as it would be in 1940, the British and French armies are able to hold the line outside Paris, and there is no Fall of France –which makes for a strategically different war from the WWII we know, not least because there is no Battle of Britain or Attack on Pearl Harbor.
Discontent grows within the German army as the Western Front is threatened and has achieved little strategically, whilst dissatisfaction with Hitler's rash decision in starting the war in the first place leads to a purge of the officer corps.
Germany is able to gain ground in Scandinavia and introduces the new Panzer III tank, but the British, the French and the Soviets are able to mount major offensives that push toward the German border.
After Winston Churchill dies in a car accident (widely suspected to have been a deliberate assassination), Rudolf Hess is able to convince the two allies to send their armies into the Soviet Union.