This has been the topic of several movies and a PC game that has been around for quite awhile now. In this one film, I lady goes back in time and kills Hitler as a baby, leaving a little jewish boy in his place, NOTHING CHANGES! World War II still happens, and "Hitler" still initiates the Holocaust.
In the PC game I mentioned, Command & Conquer; Red Alert, Albert Eisenstein goes back in time and removes Hitler from the time stream, before Hitler came to power.
World War II still happens, except this time its Soviet Russia that tries to take over the world. And in this "Alternate Timeline" the war is even worse, it lasts twice as long, and many more people die, and the war never really stops.
Yuri, a Russian general (or some kind of big wig) escapes the aftermath of Soviet Russia's downfall, and continues to be a pain in the but for the entire world for close to two hundred years.
What I am saying is that these tales are way time travel to change the past is pointless, because whatever you did already happened, and you can't change it; and conversely you can make it even worse then it was originally.
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