I think what @Renohren@lemmy.world's referring to is that India and Pakistan have, in the past, conducted nonviolent ceremonies at the border involving soldiers from each side.
https://www.youtube.com/watch?v=LixwXJpggME
I believe that the painting that you're talking about was from an American Civil War battle that was close enough to a city (Washington DC?) that spectators decided to show up to watch. A bunch of people (including, IIRC, spectators) did die. That wasn't being done with the intent of ceremony.
kagis
https://www.history.com/articles/worst-picnic-in-history-was-interrupted-by-war
On July 21, 1861, Washingtonians trekked to the countryside near Manassas, Virginia, to watch Union and Confederate forces clash in the first major battle of the American Civil War. Known in the North as the First Battle of Bull Run and in the South as the Battle of First Manassas, the military engagement also earned the nickname the “picnic battle” because spectators showed up with sandwiches and opera glasses. These onlookers, who included a number of U.S. congressmen, expected a victory for the Union and a swift end to the war that had begun three months before.
Instead, the battle that day resulted in a bloody defeat for the Union and sent the picnickers scrambling to safety.
Just to confirm, Tineye finds one match corresponding to your image, called "CivalWar_PicnicAtManassas.jpg", so I suspect that's from that battle.
I don't think that I'd call that very representative of even American Civil War battles, though, much less of all prior battles in history.
He knows how this works.
However, some of his audience in the US does not, and he's exploiting that ignorance.
What he's doing is just creating this fictional narrative where he's always being seen as fighting against some enemy that's keeping the US from being exactly the way his target audience wants it to be. It's not Trump's fault. He's pushing as hard as possible to make everything perfect. It's .
A couple of years back, when Venezuela didn't pay some Portuguese company for ham, they stopped shipping ham until they got paid. Maduro went out and accused Portugal of attacking Venezuela.
https://www.cnn.com/2017/12/28/americas/venezuela-portugal-christmas-sabotage/index.html
Every problem is someone else's fault, not Maduro's, who is fighting his very hardest for the public. Maybe it's the CIA. Maybe it's reactionaries. But it most certainly is someone else. Every problem just requires a new story about how someone is countering the Supreme Leader's effort, else everything would be perfect.
We just aren't used to seeing this kind of stuff from a US President. Trump, however, is doing the same sort of nonsense.
Consider some of the following recent Trump stuff:
Trump is considering suspending habeas corpus. The Trump administration is intentionally exploiting confusion over the metaphorical word "invasion" and the legal term. So then he's going to probably go declare suspension of habeas corpus, which he can't do short of someone invading, and then a judge is going to shoot it down, and the Trump will go tell his base that the judges are chaining him down, even though he had every right to do this, and if it weren't for radical leftist judges, there would be no illegal immigrants.
Trump warns U.S. carmakers not to take advantage of tariffs by hiking prices on consumers. Trump knows perfectly well that companies hit by tariffs are going to pass that on into price increases for consumers. But some people in the US don't, so by publicly standing up and demanding this, he can exploit that ignorance, show himself as standing up for consumers and random companies being the bad guy.
The political strategy is to always pass the buck off to someone else, and try to get as many people as possible to burn their own credibility supporting his false claims so that he doesn't run out of credibility.