I wanted to confirm the origin of the phrase "square meal." I did a NON-GOOGLE search among the many etymology web sites to confirm that it originated with U. S. Military Academy (West Point) cadets' slang in its early days. I had been informed that [at least] in the first years of West Point's existence, during meals cadets must sit "at attention" and use precise jerky motion of "feeding arm" that vaguely resembles a square or parallelogram to raise food from plate to mouth.
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I realize how ridiculous this reads. But for one who was in infantry OCS, it reads no more ridiculously than the method to move more than 200 junior candidates through a meal in a mess hall that seats fewer than 80 people in less than 30 minutes. And that method was know as "Pig Privileges." Here's how it it accomplished by the Tactical Officer of the meal:

Junior Candidates, At Ease (sit at attention). You have ten minutes to clear the mess hall (be served your meal; eat all of it; and get out.). You have Pig Privileges! (You may not use utensils. You must use both hands and just keep filling your mouth until your tray is empty, mastication optional) Carry On.
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I found several different etymology sites having origins differing from one another. I found zero corroboration for my version. Does anyone have any origin that might be considered solid, a near certainty?
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One last thing. People who were in the U. S. Marine Corps believe that Parris Island OCS and basic training to be the most "vigorous" in terms of destroying civilian mode of thought and remanufacturing as the Marine Corps' mode of thought - that is, trash one kind of "stuff" and installing a different kind. Accomplish this with absurdist routine.

"Pig Privileges" is kind've tough to beat.

I had always heard that a square meal came from the Navy (British?) where the sailors ate off a square or rectangular wood plate. Hence the term three square meals a day.

That brings to mind the saying "There ain't no free lunch". The free lunch was a regular sight in any bar prior to the Volstead act (proabition in 1919). The bars were laden with food. You bought a beer they looked at askanse for a bit but if you bought a whiskey you could eat like a king.When the amendment was repealed in 1934,spirits were now available but there was "No Free Lunch".

Square means tidy, good, orderly, fair, proper, precise. A square meal, a square deal, a square knot. Goes back to construction and took on additional uses on wooden sailing ships hundreds of years ago. Glad we could get that all squared away.

I always thought it referred to square rigged sailing ships.
What about a "square head " ?

Square head. Ya sure, you betcha.

Dave

I figured it was a meal that consisted of a meat, bread, vegetable and dairy.