When it first started by in 1995, a lot of the episodes were about Hitler and WWII because that was the footage they could afford to get and turn a profit. Most clips were public domain. Hire a writer that specialized in history, or could research it, add a few experts in the field for scale (at which time, they would interview these experts for a number of episodes, even crossing over into other programs) Why the focus on WWII? because it was possibly one of the most documented wars in history. Korea? Meh. Vietnam, still not as documented. besides, much of that footage was not in the public domain. For a few years, they had a great spinoff channel called History International. It carried actual international history, history going back much further than the US was a country. It didn't last long, and was soon retooled to be H2, where Ancient Aliens and a host of other pseudo-science programs replaced actual world history and science.It is now called Vice, and I have no opinion of that because I've not watched it. The WWII programming left History years ago, to launch another spinoff channel: the Military Channel. Now, we are left with programs like American Pickers (at least they tell a history of artifacts, but mostly US artifacts, which doesn't go back very far), Pawn Stars (again, mostly US artifacts) Ice Road Truckers (okay, that could be historical and a good special, but a realty show series?) Axe Men (HUH?) and other non-historical reality shows. FML.
Back in 1995, and the early years of the network, it was often called the Hitler Channel, but since the launch of the Military Channel, Hitler barely makes a house call there.