Back in 1972, our Basic Combat Training company was put through something called “Survival, Evasion and Escape,” which featured a simulated breakout from a POW camp, after which we were scored on how many of The Enemy’s troops we prevented from reaching friendly forces a few miles away. About halfway across, there was a river to be forded; we hit on the notion of hiding behind the farther bank, one of us every few hundred yards or so, and capturing everyone who came across. The company commander was sorely vexed, until the scores came in, and no one had gotten past us, at which time he was happy to take credit for the idea.
Which is not to say that no one else has ever thought along these lines:
For $6 billion, we could pay 120,000 sharpshooters $50,000 a year and line them up every .3 of a mile.
— The Waukegan Kid (@realjackbenny) January 11, 2019
Well, no, not exactly, as you’d have to keep those positions manned 24/7, and sharpshooters don’t stay sharp after being up all day and all of the night. So they’ll of necessity be a bit farther apart. (Our own little experience in 1972 was over with in less than six hours.)