I have a blurry memory of a fragment of some anime or cartoon from deep childhood, somewhere in 2007-2010.
My parents often downloaded pirated cartoons for me, and sometimes at the beginning there were advertising clips of other films.
In one of them I remember this plot: an aerial battle in a dieselpunk or historical setting, where two young friends or brothers were sitting in ball turrets (like on a B-17 plane), and one of them was shot to death with a machine gun. They were in some kind of aircraft, perhaps an airplane, but more likely a zeppelin, because these turrets, as I remember, were on the same ship.
I’m not sure if this clip was actually at the beginning of another movie, but I remember watching this particular clip several times, so that’s probably it.
The fragment resembled Last Exile or Sky Crawlers, but there is certainly no such fragment.
I saw that some people on reddit were also searching for this fragment, so it’s definitely not a dream, but a real memory.
Thanks!