The concept of ‘elastic defense’ goes all the way back to Hannibal Barca in 216 BC. Hannibal, a Punic military commander from Carthage, took a diverse group of Hispanics and Celts, whose knowledge of he used to fuse into his tactics, and developed the modern day ‘pincer movement’ to annihilate a big part of the Roman Republic’s army.
It was called the Battle of Cannae, and if you have no knowledge of military history like me, but it sounds familiar anyway, then it’s probably because you watch HBO, where it was popularized by Game of Thrones in the famous Battle of the Bastards episode.