I told this story in another context a few years ago, in this forum, but I'll tell it again. When I was in elementary school, the school went from kindergarten through the eighth grade. Lunch periods were staggered, with the earlier grades going to lunch at the same time, but the 6th, 7th, and 8th grades were staggered by fifteen minutes, with the seventh graders being released for lunch fifteen minutes earlier than the 8th graders. After eating lunch, we could go out and play, so most people would quickly eat lunch and head for the playground. Behind the school was the playground, which included a baseball field. Behind that was a hill. While the hill was the property of the school, students were not supposed to be on the hill, and certainly not over the top of the hill. When I was in K-5th grade, I don't think we ever went on the hill during school hours. In 6th and 7th grade, we'd do that but the 8th graders usually wouldn't allow any of the younger kids to go behind the hill, which is where they were. Since we got there first, the 8th graders would kick us out, which often involved the throwing of sticks and stones. One day, someone got the idea to strip the leaves and most of the branches from the many sumac bushes that grew there, leaving two branches forming a V. Sumac is very resilient, so when they were bent over to the ground, they would spring back with a lot of force. We gathered a supply of sticks for ammunition, and manned the sumac bushes. As soon as the 8th graders came over the hill, we let them have it with a barrage of sticks propelled by sumac catapults. I think we ended up getting beaten but we had made a good showing so it felt like a victory.
The over-the-hill experiences were a big deal then because, until seventh grade, we never considered violating the rule about going over the hill. In the earlier grades, we'd go onto the hill perhaps, but not over it. But I suppose whoever was supervising us when we were younger was probably more diligent about it. Starting in the seventh grade, we'd go through lunch in about five minutes so we'd have time behind the hill before the eighth graders were let out.
The tribalism and warrior behaviour truly is genetic, ain't it? I recall some of that stuff, but it was not centered so much at school as it was other popular places (like the railroad bed when they first tore up the tracks for the C&O Railroad where I lived.) The tracks were in a gully at one stretch, so some days one side would be riding dirt bikes through the gauntlet of thrown dirt clods (I don't ever recall rocks being thrown down), and on other days the sides would trade places. It was never organized, it "just happened." The worse thing we would do is tie firecrackers to the dirt clods, light the fuse and then throw them. No damage was done, but the effects were the stuff of legend.