The best example of contemporaneous politics screwing up history is the case of Richard III. Our biggest sources on Richard come from two people: Thomas More and Shakespeare. Both of them wrote about Richard while living under the descendants of the man who defeated Richard. It is only recently that anyone has suggested that Richard III wasn't the pure evil hunchback of London.
Current politics, of course, is the more obvious perpetrator against truth in history. For example, the myth that "white people have never suffered oppression" ... Oh? Really? So, all of that "No Irish need apply" crap in the late 1800s was meant for, who? Hispanics? Please. The last 150 years of history have been all about oppression. At some point, somebody had been oppressed by somebody else.
But yes, modern political agendas are probably the major problem when it comes to getting to truth. As I said yesterday, politics is probably the true root of all evil. Politics equals power, after all.
The easiest example is Dan Brown, who screwed up all of Roman Catholic history, neopagan history, and anything else that didn't match his screwed up, f**ked up agenda. Seriously, he managed to make Newton excommunicated by the Catholic Church "for the theory of gravity" .... Does anyone have a problem with that? Anyone? Aside from the fact that Newton stole parts of his theories from Catholics? The answer is: NEWTON WAS ANGLICAN! NOT CATHOLIC.
You want other examples? Look at Inherit the Wind, a play, and later two movies, a fictionalized version of the Scopes Monkey Trial. And by fictional, I mean full fantasy. The real Scopes was a teacher using an interesting textbook with a peculiar outlook on evolution -- which suggests sterilizing hillbillies, rednecks, and other degenerates. So ... yeah, charming, huh? Can you imagine why a bunch of religious folks in the Bible belt would find this somewhat objectionable? And yet Inherit the Wind makes it look like the poor innocent teacher is being sucked into a bad situation by ignorant redneck Bible thumpers.
Yeah, charming, isn't it? But modern politics dictates that the red necks are the enemy of Progress! And Progress! is everything. And evangelicals are backwards! They're all the same! They! Are! Too! Stupid! To! Live!
And screw! You! And your blanket! Generalizations!!!!
.... Okay, it doesn't work quite as well as I had in my head. But I'm writing this at an odd hour.
My point is obvious: politics will screw up almost any study of history. The politics of the day will screw up how things are reported, and modern politics will screw up how they're summarized to you, the reader. Usually, "the victors write the history" isn't an excuse, as there are generally no permanent victors -- though in the case of Richard III, he seems well and truly shafted by history.
The usual excuse for idiots like Dan Brown and others of his ilk is that "but we need the changes for the drama."
If anyone, and I mean anyone, tells you that history has been sacrificed for narrative purposes and drama? They're lazy bastards who haven't done enough research into the subject matter. Trust me, I'm a historian. If you think "This story is boring, I need to change things to spice it up," screw you. I'm a history, I know when I'm being lied to. And trust me, that is the surest way to piss me off.
Politics is the enemy of Truth. As God is the Way, the TRUTH, and the Light, I have no problem concluding that politics is the enemy of God Himself.