Compared to the machines of today, combat aircraft from the early 1940s were pretty simple, while the pilots were simply awesome. No heat-seeking missiles. No laser-guided anything. No radar or chaff to confuse it. It was a simple machine with some simple firepower (by today's standards), the pilot's senses and skills, and lots of training. There were no time outs, no "Oh, that's not fair!" and the rules were very straightforward: fly or die.
The single safest place a pilot could find himself was above and behind his opponent. This gave the "higher" aircraft the opportunity to react to actions of the "lower" craft. At no point could the disadvantaged plane maneuver without the advantaged plane seeing it and reacting accordingly. If the enemy turned left, he turned left. A hard right was followed by a hard right. If the enemy dove and went right and then quickly came back to the left, the advantaged pilot could follow. Assuming the advantaged plane was more maneuverable and it's pilot was at least good, the disadvantaged plane was totally at it's mercy.
Above and behind the opponent is a safe place to be.
Birds know this, and do the same thing.
I was heading to the hawkwatch yesterday and found myself witnessing something I have seen too many times to count: a "ball" of passerines above a hawk. In this case, it was a mob of Starlings trying to maintain position over a Red-shouldered Hawk. (Looking for these masses of small birds is a standard trick for hawkwatchers. If you see a wad of birds on the horizen, look below them. They are likely reacting to the danger.)
While I don't think the hawk was a threat to the starlings, I gathered that the starlings were not going to take any chances. No matter what the lone bird did, they responded. At every opportunity, they shifted and twisted and flapped feverishly to get to the safe position. Above and behind. The neat part was that all the birds were reacting the same way and they were all trying to jockey for the same position. Above and behind. The shimmering of their wings was quite cool in the bright sunshine. ( I have seen this effect with thousands of blackbirds. Awesome.)
Did they talk to their wingmen? Did they get the latest and greatest information on enemy tactics from their intelligence officer? Did they spend countless hours in flight school? Well, no, no, and , yes, depending on how you look at it, I guess.
The flight school would be Mother's Nature Flight School. Eventually, all "pilots" are trained to get themselves into that sweet spot. If it worked for them the last time they encountered the enemy, it might work again. Don't screw around and don't get caught out of position. Do it quickly and efficiently or it might be the last thing you do. Over time, all the graduates that survive "Flight School" pass along their knowledge to future "pilots." Not so much by training and classwork, but by gene flow.
It's all the same, really, with combat pilots or birds. There is the one place to be - above and behind.