All of us grow as we age; some more than others. Things we thought simple and obvious when we were children turn out to be infinitely complex. Judgments we handed down when we were innocent later turn out to be self-righteous piffle. Uncles we thought were hilarious when we were 6, when we are 15 turn out to be insufferable. If you live long enough, your life gives proof to the Firesign Theatre dictum: “Everything you know is wrong.”

This is the evolution of — what? Of an understanding. A widening of the historical record. I’m using the Second World War as my exemplar. I have been aware of it from my earliest childhood, but my understanding of it has changed radically over the decades.

I was born just after the war ended, and it was an immediate presence in those years. My childhood featured the shabby remainders of that war gotten from the proliferation of war surplus stores. We all played war, and the nerdier kids were condemned to play Japs and Krauts, while the alpha kids were Americans. I envied my friends who had helmet liners, machetes, canteens or drilled and emptied hand grenades to play with.

My father saw France and Czechoslovakia in that war, although he downplayed his part in it. He had several war souvenirs that were kept in the basement: a German helmet, an SS dagger, pair of binoculars, a Walther PPK pistol. I was fascinated by them, and pulled them out to play with. (When he found out I had been playing “war” with the PPK, he immediately took it and sold it to get it out of the house). These things were catnip to a little boy.

This was the early 1950s, and I learned about World War II through movies shown on television. This was the war of John Wayne and William Bendix. The Americans were the heroes; the Japanese and the Germans were the villains. It was an easy call; there were the good guys and the bad guys.

The version of Hitler that shows up in these films is insubstantial. When mentioned at all, he is satirized as a clown with a funny mustache, but most often the Nazis are an undifferentiated enemy with nefarious aims. Little distinction is made between Germans and Nazis. We argued over which way the swastika bent, and whether they were “knot-sees” or “nah-zees.”

When the German war aims are mentioned, it was that they sought “world domination.” When the movie is set in the Pacific, the Japanese war aims were never mentioned at all: They were just evil and our enemy.

There were documentaries, also. On TV, there was also the resonant voice of Leonard Graves and the music of Richard Rodgers on Victory at Sea, and a Saturday morning filler program produced by the Army called The Big Picture. Both fed a version of the war that was about the United States defeating its enemies.

It was in those Army documentaries that I first saw images of the liberated concentration camps when I was a boy. I was horrified — and fascinated — by those piles of dead naked bodies bulldozed into mass graves by the American soldiers, and the spindly, glaze-eyed skeleton-survivors. I don’t know how these images affected others, but in my tiny 6-year-old brain, they were the fountainhead of moral development: Those images are indelible; I can draw them up in my mind anytime. Nothing from my childhood has such potent emotional power as the memory of those films. But the Holocaust was a separate issue, barely related in my boyish brain with the war my father had fought. Only later, did the Holocaust become central to my understanding of the war, of Nazism, of Hitler.

By the time I was in the seventh grade, my interest in the war had changed: In typical adolescent (male) fashion, I became hypnotized by the machinery and regalia of the war. I learned the names of each type of Panzer tank, fighter plane, each sort of submarine and corvette, destroyer and cruiser. I drew them endlessly in stereotyped scenes learned from primarily from Sergeant Rock comic books.

By then, I was also becoming aware of the centrality of Auschwitz. But German anti-semitism made no more emotional sense to me than the “world domination dictator” image of Hitler. I grew up in northern New Jersey and my Boy Scout troop leader was Mr. Weinstein. I knew many Jewish people and I could not see any difference between them and the Italians, Irish, Germans or South African families sprinkled through the suburban neighborhoods. Anti-semitism seemed no more possible than men in the moon.

The version of the war that persists in the American imagination is the one in which Americans, with a little help from England, beat back Hitler and won the war.  D-Day was the turning point. There was a niggling awareness that there might also be some fighting on the eastern front, and that somehow the Soviet Union was our ally in the war, despite their being “godless communists.”

This version was filled with stories of American heroism in the war. We won, it was implied, because democracy always wins. It was our system vs. their system, and ours was more virtuous. After all, God was on our side (despite the Wehrmacht beltbuckles that read “Gott mit uns.”)

I had read a good deal about the war and had finally come to the conclusion that perhaps D-Day was not the central turning point of the war and that perhaps the conflict with the Soviets was a bigger deal than the war in France. (This is not to diminish the efforts of the Allied soldiers in western Europe, but to recognize the balance of the death and fighting was in the east).

I began to see World War II as the “Great Patriotic War,” a war primarily between Germany and the Soviet Union, with the Western Allies as a sort of sideshow. All those riveting TV documentaries about D-Day and the retro-movie version of the war in Saving Private Ryan seemed like empty chauvinism. How many Americans died in the war? About 400,000, which is a staggering number until you compare it with the number of Soviet forces killed: 10 million. If you add in the civilian war deaths, the number rises to  27 million. That is nearly 14 percent of their total population. In the U.S., that percentage is less than one-third of one percent. (Again, I don’t mean to diminish the enormity of the American suffering or the part played by our soldiers, but to put it into the larger context of the war horror).

On D-Day, American deaths were about 2,500, roughly the same number as died in the World Trade Center on Sept. 11, 2001 (and roughly the same number who were killed in the attack on Pearl Harbor Dec. 7, 1941), but consider the battle of Kursk in the Soviet Union, when some 10,000 Germans were killed and the Soviet deaths estimated at three times that. Or the Battle of Stalingrad, which admittedly continued over several months, but wound up with nearly 2 million casualties. If there was a turning point in the war, it was Stalingrad, not D-Day. Germany never recovered.

Forgotten in all of this is Japan. When I was a child, it was clear that the Japanese were treacherous people who designed the deaths of Americans, presumably for irrational reasons. They were a crazed nation of  squint-eyed, buck-toothed people insanely loyal to an emperor.

World War II was in most books a single entity with combat theaters in Europe and in the Pacific. But at some point, I came to understand that there were really two unrelated wars being fought concurrently, or rather that the two wars overlapped. The European war began in 1939, if you were Polish, 1941 if you were Russian (June 22) or American (Dec. 7). But the Pacific war had begun in 1931 with the Japanese invasion of Manchuria and turned into the so-called Second Sino-Japanese War beginning in 1937. Just as in Europe, where we glory over D-Day and forget the millions who died in Eastern Europe, so in the Pacific, we remember Iwo Jima and Guadalcanal and tend to forget that the real misery was felt in China, where the war death estimates run from 10 million to 25 million. (It should also be remembered that until Pearl Harbor, Germany and the Soviet Union both allied themselves with the Chinese against the Japanese.)

But the one question I could never quite answer to my satisfaction, the issue I could not quite understand was: What were the goals of the Axis powers? What did they hope to accomplish?

The standard answer was: World domination. Hitler wanted to invade Europe to achieve power. Why he might want to conquer France was a mystery. Why he bombed London never made sense. And that was just the Germans. The Italians hardly entered the equation. They were an afterthought. And finally, it was never clear what sort of domination the Japanese might be after.

In the Warner Brothers cartoons I was weened on, Hitler, Tojo and Mussolini were three comic villains with the same aim: world domination. (No one asked if they had accomplished this goal, whether they would turn their rifles on each other).

Hitler was, in this view, hardly different from the nefarious Fu Manchu or Dr. Mabuse or Ming the Merciless. Why any nation would bend to the will of such a madman was an enigma.

Wars are political and economic. We remember them militarily, but they are gestated through power and money. Now that I am an old man, I no longer see World War II as the “Good War” — the American version — or the “Great Patriotic War” — the Russian version — but rather as The War between Hitler and Stalin over Poland.

Poland has rolled around eastern Europe for centuries, expanding and shrinking, becoming an empire and disappearing altogether. You could make an animated map showing how over time Poland moved east, then north, then west like a ball of mercury on a plate, then evaporated like a dried-up puddle. In western Europe, nationality conveniently tends to follow ethnicity. France is filled with the French, the Netherlands are filled with the Dutch. But throughout eastern Europe, ethnicities are scattered like confetti. There were Germans in Poland, Poles in Ukraine, Lithuanians in Poland, Russians in Lithuania, and Jews all over. It made national borders more arbitrary than they are in the west. Much of Hitler’s plan before the war broke out in earnest concerned bringing ethnic Germans together under one nation-state. Hence the Anschluss and the annexation of the Sudetenland in Czechoslovakia. His ostensible aims were to “protect” the German people from persecution by non-Germans. The Nazi slogan was “Ein Volk, ein Reich, ein Führer” — One people, one country, one leader.

“Ein Volk” — this was a nearly mystical idea of race and genetics. Hitler believed in two things that were current in his age. One was Social Darwinism, that competition was not only between individuals, not only between species, but between “races,” or genetic bloodlines. His Germanic race was in competition with all other races, and only the strong would survive. Second, he believed in a neo-Malthusian sense that as population increased, food production would begin to fail. And, as Germany industrialized, fewer people were producing food, and less land was given to farming. These two things were behind his announced need for “Lebensraum” — living room. He proposed not only to aggregate the Deutsche Volk under one political system, but also to annex new farmland to Germany and repopulate that land with German farmers.

In this, one ventures to say, he was little different from American Manifest Destiny in the 19th century. As we proposed forced migration of Native Americans and to appropriate their lands, so Hitler proposed to move Poles and other non-German people out of his section of Poland and repatriate a growing population of Germans into it.

He faced two international political problems with this plan. The Soviet Union would likely object, and the allied forces of western Europe had a treaty to defend the independence of Poland.

To eliminate those problems, he made a pact with Stalin — the Molotov-Ribbentrop non-aggression pact — which freed him up, he expected, to face the armies of France and England that intended to protect the sovereignty of Poland.

In reality, there was an unpublished portion of the Molotov-Ribbentrop Pact that split Poland in two, with one half going to Hitler, and the remains going to Stalin.

So, when Hitler invaded Poland on Sept. 1, 1939, he planned also to turn his Blitzkrieg on France, which he neutered in 1940, taking over most of western Europe save Great Britain and the neutral countries of Spain, Switzerland and Sweden. This meant he thought he no longer had to worry about a two-front war. In this sense, the whole war in western Europe was a sideshow to the real carnage.

When the forced immigration of Poles, Jews and other non-Germans proved problematic, and after Hitler decided Blitzkrieg could bring him not only Poland, but also most of the European territory of the Soviet Union, he invaded eastern Poland (by then, a part of the Soviet Union) and headed for Moscow.

A separate industry developed to deal with the displaced peoples, which, by Hitler’s racial thinking were Untermensch, or lesser humans, and with his own propaganda blaming Jews for the loss of the First World War, and the “Jewish Bolshevism” of Communist Russia, his Nazi planners came up with a “final solution” for what to do with all those unwanted people. Six million Jews were exterminated over the course of the war, mostly from 1942 to the end of the war. But also nearly 2 million ethnic Poles, 3 million Ukrainian and other non-Jewish victims.

(Timothy Snyder’s 2010 book, Bloodlands, covers all the deaths in the tragic lands between Germany and Russia from the 1930s through 1945, including the Holodomor — the deliberate starvation of between 3 and 7 million Ukrainians by Stalin’s order. In all, between Hitler and Stalin, Snyder estimates that some 14 million non-combatants were murdered for political reasons between 1933 and 1945. The numbers are all estimates; the death was so pervasive, accurate records for most deaths were impossible. And these 14 million were all separate from the military deaths of the war.)

What I have written here is an obviously very simplified version of things. Almost every sentence here could be expanded into a book. I have left out many important things (not the least of which is the bifurcation of Europe after World War I into camps espousing Communism and camps promoting Fascism. For a time in the 1930s, it even looked as if America was going to have to choose between them).

This is a lot of words, all to show the slow development of ideas about the war, from childish to mature, from simple and unexamined to complex and nuanced. The case I am trying to make is that this is true not simply for my pathetic little understanding of World War II, but that this kind of growing complexity is symptomatic of getting older, seeing more of the world, and tying it all together.

I could have chosen almost any subject and gone on at length about how my understanding has changed, widened, saddened. For, if there is anything that results from broader experience — which is what getting old gives you, want it nor not — is the sad truth expressed in Jean Renoir’s 1939 film, Rules of the Game, spoken by Octave (played by Renoir himself): “You see, in this world, there is one awful thing, and that is that everyone has his reasons.”