Start with one volume
The Second World War · Antony Beevor (2012)
The whole war in one book, and genuinely global: the Pacific and China get proper weight rather than a closing chapter. Beevor moves between the strategic map and the individual account better than anyone currently writing, and he does not flinch from what armies on all sides did to civilians.
Then one campaign, closely
Stalingrad · Antony Beevor (1998)
The book that made Beevor's name, built on Soviet archives that had just opened. Five months, one city, and the clearest demonstration in print of what industrial war does to the people inside it. If you read one campaign history, read this.
Then the killing
Bloodlands · Timothy Snyder (2010)
The lands between Berlin and Moscow, where fourteen million non-combatants were killed by two regimes between 1933 and 1945. Snyder's move is to refuse to treat the Nazi and Soviet killings as separate subjects, because the people living there did not experience them separately. Contested by specialists on the framing; essential on the facts.
If This Is a Man · Primo Levi (1947)
Published in the United States as Survival in Auschwitz. Levi was a chemist and writes like one: precise, unraised, concerned with what the camp did to the idea of a person. The most important book on this list and the shortest.
Then the ending
Hiroshima · John Hersey (1946)
Six survivors, thirty thousand words, published a year after the bomb and read aloud on American radio in full. Hersey simply reports what happened to six people, which is why it did what a decade of argument could not.
Embracing Defeat · John W. Dower (1999)
Japan under occupation, 1945 to 1952, and the making of the country that exists now. The rare book about an aftermath that is as good as the books about the war. Covered further on our Japanese history shelf.
What about Shirer
William Shirer's The Rise and Fall of the Third Reich (1960) sold in the millions and shaped how two generations understood Nazi Germany. It is a journalist's book, written by a man who was there, and its interpretation of German history as a long road to Hitler has not aged well. Read it as a period document. For current scholarship on the regime, Richard J. Evans's Third Reich trilogy is the standard.
Fitting the war into a real life
This is heavy reading and it does not reward bingeing. A page a day of something wider keeps the perspective open: 365 Days of World History (ours, flagged) runs one day in history per day across the whole record, and the world history shelf puts the war back into the century around it.
Common questions
What is the best single book on World War II?
Antony Beevor's The Second World War. One volume, properly global, and it holds the strategic picture and the human one at the same time.
What is the best book about the Holocaust for a first reader?
Primo Levi's If This Is a Man for testimony, and Timothy Snyder's Bloodlands for the scale and the geography. Levi first.
Is The Rise and Fall of the Third Reich still worth reading?
As a period document by a journalist who was there, yes. Its argument that German history led inevitably to Hitler is no longer accepted. Richard J. Evans's trilogy is the current scholarship.
What order should I read these in?
Beevor's one-volume history for the shape, then Stalingrad for a campaign, then Levi and Hersey for the view from inside. Snyder any time after the first.