Words on strike, The letters on rampage, Lines split, A writer stands down. According to the following source the origin is from military jargon and its first usage dates back to the beginning of the 20th century. Stand down: is one of several specifically military uses of “stand” that include “to stand to one’s arms,” meaning “to maintain one’s position in the face of an attack” (the source of the idiom “to stick to your guns,” meaning “to not give in” in an argument, etc.), as well as “to stand to arms,” meaning to assume combat readiness and prepare for action. “To stand down” is the opposite of “to stand to arms,” and means to go off duty or relax from a state of readiness (“‘Stand-down’ was the corresponding order at the end of the Danger Period, used in like manner as an expression for a definite point of time,” 1925). The “down” in “stand down” doesn’t mean literally taking a seat, any more than the command “at ease” means to lounge on the nearest couch, but the contrast is to “on duty” status and alert readiness.
