Here’s an example of a general knowing the details and using it to win a battle.
During the First Punic War, the Carthaginians used elephants in battle. The Romans did not.
Elephants are big and hard to kill and they can cause a lot of damage when they charge. If you’re a soldier with a sword or a spear you do not want to be holding a line against an elephant.
On the other hand, elephants don’t have a personal stake in the outcome of the battle. They don’t really care if their side wins or loses. And they don’t like be stabbed or slashed. So all things considered, an elephant would just as soon not fight. But the guy riding the elephant is able to convince the elephant to attack.
And so the battles would go. The Carthaginians would sent a bunch of elephants charging at the Romans and the Romans would try not to get crushed while driving the elephants off. After the elephant charge was done, the main Carthaginian army would attack. The Romans, already reeling from the elephant attack, would often lose.
Up until the Battle of Zama. At Zama, the Roman General, Scipio, tried something different. When the Carthaginian general, Hannibal, set his elephants charging at the Roman line, Scipio gave the order and all of the Roman soldiers stepped aside and created clear paths through the Roman army. The elephants were of course supposed to charge at the soldiers but when they saw these open paths, they ran for them instead. The riders tried to get them to attack but the elephants just charged through the army on the open paths without killing anyone and ran out the other side. The Roman soldiers then stepped back into formation and went on to win the battle.
It was a risky maneuver. The elephants might have charged the soldiers like they were supposed to and were in the habit of doing. Worse yet, they might have started down the open paths but then been brought under control by their riders. If that had happened, the effect would have been devastating. Rather than attacking the front of the Roman line, the elephants would now be attacking in the middle of the Romans and would have caused much greater casualties than they usually did. And the soldiers at the front of the line would have been caught between raging elephants behind their backs and Carthaginian soldiers to their front. There would probably have been a panic and complete rout.
But it worked completely. And it was not something Scipio could have learned. He didn’t have any elephants of his own. The Carthaginians, who had elephants, had never thought of this idea (and Hannibal was no dummy). Scipio had just observed elephants in previous battles and seen how they acted and how their riders acted. He then used his experience to create a plan.