The oldest anime I ever watched, back then it was mostly doing whatever Disney or Fleischer were doing but with a Japanese setting (I know it's more complex than that but whatever). In this case it's a short about Mickey Mouse invading an island and the natives fighting against the foreign invader. Despite my love for disney hate, I gotta share what user Systemhalodark said in the comment section of the video: "The irony, considering that this is what they were doing to China at the same time." This is from a period before the concept of anime was created, which happened somewhere in the 1960s or1970s, so it's kinda even hard to think of it in "anime" terms. It's really just a simple animation (I'm writing this just to fill the review length quota)