= 4. Nares says because “at great dinners ... the company was usually arranged into fours.” That four made a mess is without doubt. Lyly expressly says, “Foure makes a messe, and we have a messe of masters”
(Mother Bombie, ii. 1). Shakespeare calls the four sons of Henry his “mess of sons” (2 Henry VI., act i. 4); and “Latine,” English, French, and Spanish are called a “messe of tongues” (Vocabulary, 1617). Again, Shakespeare says (Love's Labour's Lost, iv. 3), “You three fools lacked me ... to make up the mess.” Though four made a mess, yet it does not follow that the “officer's mess” is so called, as Nares says, because “the company was arranged into fours,” for the Anglo-Saxon mesc, like the Latin mensa = table, mes Gothic = dish, whence Benjamin's mess, a mess of pottage, etc.
Mess, meaning confusion or litter, is the German mischen, to mix; our word mash.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894