A series of books by Harry Turtledove. The Darkness series takes the events of the Second World War and resets them, with minor modification, in an archetypal fantasy world, but an industrialised one. For example, dragon riders replace fighter pilots, but they are as strictly regimented and controlled as OTL air forces, unlike the more individualistic pre-industrial approach more common to fantasy worlds.
A secondary point is that national characteristics are randomised among the nations, possibly in order to present a more objective look at the war. In a particular piece of irony, the Darkness world's equivalent of the Jews, the Kaunians, show Aryan characteristics such as being tall, blond and blue-eyed. Ideology is mostly ignored in the books, except racism - every country is a monarchy of some sort.
Turtledove also reverses a lot of geography - the main landmass, Derlavai, is in the southern hemisphere. Forthweg (Poland) and Zuwayza (Finland) are hot countries, while the Land of the Ice People (North Africa) is very cold. West and east are reversed, so the equivalent of the Eastern Front is fought the other way around.
Although the concept behind the Darkness series is interesting, it is thought by many that Turtledove unnecessarily padded it to squeeze more books out of it, and it could have been told better with fewer words.
Turtledove's inspiration may well have been J.R.R. Tolkien's frustration with people assuming The Lord of the Rings (which inspired Turtledove in his youth) was an allegory for WW2. Tolkien pointed out how different the story would have been if it had been intended to be an allegory for WW2: what Turtledove has done is actually write that story.
Into the Darkness
Through the Darkness
Rulers of the Darkness
Jaws of Darkness
Out of the Darkness
A list of analogues in the Darkness series:
Algarve is Nazi Germany. Its racial and cultural characteristics are stereotypically Celtic (especially Scottish) and its language is Italian.
Derlavai is the main continent, equivalent to Eurasia. It lies entirely in the southern hemisphere. The war in the series is referred to as the Derlavaian War, reflecting an alternative name for WW2 in OTL, the Eurasian War (also used in the Draka series).
Forthweg (pronounced Forthway) is Poland, but speaks Old English. Among its native people are many Kaunian colonists from the days of empire, who take the role of the Jews. They speak Lithuanian.
Grelz is Ukraine, but speaks German along with Unkerlant.
Gyongyos is Japan, though in a simplified form that ignores China and gives Japan a large continental holding. It speaks Hungarian.
Jelgava is the Low Countries. It is a Kaunian nation, equivalent to both Romance and Jewish in the Darkness series, and speaks Latvian.
Lagoas is Britain, but shares a continent with Kuusamo (the United States). It is an Algarvic nation and speaks Portuguese.
Kuusamo is the equivalent of the United States, but is racially East Asian and speaks Finnish. It is ruled by seven princes rather than a single king.
The Land of the Ice People is North Africa, but is an icebound southern continent and its people speak Hebrew.
Ortah possibly represents Switzerland, and speaks Hebrew.
Siaulia, on the equator, represents sub-Saharan Africa and is mentioned only peripherally as a minor colonial front.
Sibiu is Denmark and Norway. Racially and culturally it is close to Algarve, being 'Algarvic', but speaks Romanian.
Unkerlant is the Soviet Union, but its people speak German.
Valmiera is France. It is a Kaunian nation, equivalent to both Romance and Jewish in the Darkness series, and speaks Latvian.
Yanina represents both Italy, and Germany's minor allies on the Eastern Front. It speaks Greek and is also culturally Greek.
Zuwayza is Finland, but its people are black, do not wear clothing, and speak Arabic.
Behemoths, great saddled beasts with armoured hides and equipped with powerful weapons, are tanks.
Crystals, small mass-produced crystal balls, are the equivalent of radios, but you can see the person you're talking to as well as hear them.
Dragons are fighter and bomber aircraft.
Eggs are bombs. Note this appears to be a nickname rather than them being an actual egg of a creature, as they are said to have metal shells and be manufactured in factories.
Egg-tossers, catapults that fling eggs, are artillery.
Leviathans, whale-like beasts rode by specialists who use them to attack ships from below, are submarines.
Sticks, a sort of mass-produced magic wand used by infantry, are guns. 'Heavy sticks' are cannons mounted on behemoths (tanks) and used as anti-aircraft weapons.
Like many of Turtledove's works, the magic in the Darkness series runs according to two fundamental laws, the law of similarity (two similar-looking or biologically related things are magically connected) and the law of contagion (two things that have touched are magically connected). One plot in the Darkness series concerns a magical equivalent to the Manhattan Project, in which the new theory making nuke-equivalents possible is based on finding a deeper connection between the two laws.
A network of ley lines criss-crosses the world (a concept found in folk magic) and mages in this world can make ships and vehicles that can draw power from them and hover along them. On land these are the equivalent of trains on railways lines. At sea, unusually there is nothing directly equivalent to this from OTL: hovering ships fly along the ley lines and normally fight their battles at junctions between them. These movements can be detected by mages. At one point the Algarvians pull off a surprise attack by building a fleet of 'old-fashioned' conventional sailing ships that do not use the ley lines and thus cannot be detected.
Although the Darkness series is primarily a WW2 allegory, there are some differences from WW2 as we know it. These include (spoilers):