Didnt they line the men up of a particular unit that had lost a battle, and randomly pic one guy and count to ten, then repeat and every tenth guy was killed. At least thats how I heard the Romans did it. Thats where the term “decimation” came from?
Yes
The term is also applied in 20th century infantry assaults. As a rule of thumb, the defense has a 3:1 margin over an attacking force and if 10% of either side are killed on the initial assault, the battle is a route.