While the occurrence of an event could (arguably) not be open to debate, the analysis of causes leading up to it - and the interpretation of its larger meaning - is very much open to individual interpretation. That is why History teaches us
nothing.
History is nothing more than a story (mostly told by the "winners") in which the status quo of the winner is rationalized and justified. In short, things didn't just get to be the way they are "because." According to most historical accounts, things are the way they are today because some gifted and inspired individuals set in motion a chain of events in accordance with the
Divine Plan for the Rightness of Things, and the rest...well...the rest is history.
That's why it's important to identify who is telling the story. It's not so much
a history of something like WWII as it is
who's history of WWII.
Humans tell stories about themselves in order to put themselves in the best possible light. And a frank admission we were lucky doesn't work too well when you're creating a mythos your nation or people can believe in.
People will kill each other over real or perceived threats, property, and money. But they will usually only go to war over an idea. Economics are almost always at the root of human conflict. But in most cases it takes the tinderbox of an idea (i.e. fatherland!, traditional family values!, blasphemy!, treason!, freedom!, evil!, communism!, terrorism!, capitalism!, ) to set the wheels in motion.
The US would have never marched into Iraq (as opposed to just Afghanistan) if it were justified purely in economic terms. It took about 3000 civilian deaths, a wave of national shock and outrage, several falsehoods and exaggerations promulgated through official channels, a challenge to conduct a global crusade against all that is evil - and a political cabal that was willing to put it to use. Our history books will tell that story our way. And it will always be told (by us to us) that way, whether or not we later decide to revise or reinterpret it (like we have the Civil War). It's OUR story. (People in the Mideast will have their own version too.)
So while it's good to look at history, don't expect it to teach us much. Most of what passes for history is a polite fib at best. And always will be. The actual fibs told will simply change with the tenor of the times. And most people, at some level, know that.