A subaltern’s lunch, according to old military slang, is a glass of water. We kind of explained why on Twitter when that fact popped up yesterday, but for the inquisitive among you here’s a little more about it.
The word subaltern itself derives from the Latin subalternus, which literally means ‘under every other one’. When it first appeared in English in the sixteenth century, it was a term used in logic to refer to a logical proposition or statement which is implied by another statement (known as the superaltern), but is not itself implied by it in return. “All cars have wheels”, the superaltern might say, implying that the subaltern statement “some cars have wheels” was ultimately true. Saying “some cars have wheels”, however, does not conversely imply that “all cars have wheels”. Only the superaltern, ultimately, has the power to do that.
In the sense of something that works or operates at a lower level to something else, the word subaltern was subsequently adopted into military terminology in the early 1600s, when it began to be used as a general term for any officer ranked below a captain. The term never came to be applied to any rank specifically, and so could be loosely applied to anyone either ranked or ranked between lieutenant, at the highest, and officer cadet at the lowest—subsuming the ranks of second-lieutenant, infantry ensign, and cavalry cornet among them.
No matter to whom it was applied, however, the implication was always that the role of subaltern was a somewhat lowly, undervalued and underpaid one. And a subaltern’s lunch was just about the lowliest lunch you could imagine.
“A glass of water and a pull at your belt” was the old notion of a subaltern’s lunch. It implied that young officers were compelled to be thrifty and constantly wore uniform. In the days when mess bills were closely scanned luncheon was an expensive extra. Now, of course, a young officer does himself well upon all occasions, and lunch is perhaps the cheeriest and most ample meal of the day. A now distinguished veteran, who joined the Artillery long before the Crimean War, has told me of his frugal diet at all times but dinner. He breakfasted in his own room, made his own tea, and ate the better part of a twopenny loaf with marmalade. For lunch, if there was any of the loaf left, he ate it ; if not, he tried the device quoted above; but in prosperous times he substituted a glass of Marsala for “the nasty stuff you wash your teeth in,” as some famous wine-taster called water when it was submitted to him blindfolded.
Baily’s Magazine of Sports & Pastimes (1897)