I've never heard of garde before, so thanks for the background OP.
On the topic of check, I always announce it. Every single time. When people do it to me (obviously I've seen it) I never take it as patronising. I consider it a part of the game, and have actually been getting in the habbit of saying Shah (Meaning king in Persian) instead of check to some old Eastern European players who also say it.
In any case, I find saying check is courteous and gentlemanly (which I attribute to chess).
Garde: Old and Irrelevant or Just Good Sportsmanship?
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I have never heard of the expression "garde" but i do routinely say check. It's a deeply ingrained habit since i was taught as a child that it was mandatory to provide the warning when your opponent is placed incheck. Indeed, i recall playing tournaments in the 1980's and early 1990's and saying check without being criticized for it. I recntly started playing tournaments again after a 30 year hiatus. During a recent USCF tournament, my opponent -- a 10 year old boy -- told me that saying check was unnecssary and "irritating.". I was taken aback but tried to refrain from saying check during a long series of checks before winning by checkmating him. Later i asked one of the tournament directors about the rule/practice with regards to announcing check, and he confirmed that it was not required. However, he indicated that saying check was not against the rules unless you do so in a fashion designed to distract or irritate your opponent.
So many events are out of the board and the position. A computer won't care about the tone of your voice when "checking", if it is offending or not.
The paleocephalic brain is overstimulated by some signs that your opponent is reducing drastically your advantage. For the "old brain", checkmate means that you die, literally, that your investment leads eventually to a total loss. It takes some minutes to accept that...you're still alive.
So the remark of president Lincoln : I don't care about your loss, I care if you are able to accept it. The whole meaning of it can be : at which degree can you really accept? 
cabadenwurt wrote:
Thanks to the OP for this thread as it answers a long standing question for me. I learned to play Chess back in 1967 while in High School and we did not use any type of En Garde warnings. However I remember playing a couple of games with my Step-Father in the mid-1970s and he did use the rule. At the time I suspected him of making up the rule as a joke in the game ( he had a odd sense of humor ) and since that time nobody that I've played has ever mentioned that rule. I believe that my Step-Father learned the game from his Grandfather who then would probably have picked up the game before the year 1900. So the rule would be an older rule to be sure and I'm glad to have this mystery solved at long last.
--- In my case not via a time-machine but thru playing against older relatives, but time moves on. For example does anyone still address an older Lady as Madam or Ma'am ? 
I LEARNED to use the term "en garde" when I LEARNED to play chess at Colorado Academy in the 4th grad in 1964.
I still use it today, for the same reasons the author expressed.
Is it appropriate to announce a checkmate?
Yes, I announce checkmate with the disclaimer of "I think this is checkmate"?
Just in case I missed something and I think it shows some humility & compassion on my part for my competitor.
KnogKnebronson wrote:
Yes, I announce checkmate with the disclaimer of "I think this is checkmate"?
Just in case I missed something and I think it shows some humility & compassion on my part for my competitor.
Yes. I read of an arbiter complaining of successful false claims of checkmate.
When an opponent with apparent confidence announces checkmate, and that´s not true - a check does exist, but it is not a mate because the player in check has ways out - it is by no means unknown for players to fall for it and give up, rather than notice the ways out of check.
That is interesting story about the arbiter and the "false checkmate". I would have never thought of that angle.
Wow, what would be the honor in winning like that?
Thank you.
KnogKnebronson
RoyalFlush1991 wrote:
In my opinion, "garde" seems quite a bit over-the-top for sportsmanship. I would not mind my opponent saying it (quietly) but I would not stoop to such unneccesary admonitions. Quite honestly, it is a fair assessment that no one over 1500 USCF should overlook their Queen being en-prise and still conisder themselves worthy of such a rating. As previously pointed out, repeated "gardes" would be extremely annoying during sharp tactical periods and if you are not going to say it everytime, might as well leave it out in the first place. On another note, in the very sensitive and tense world of chess competition where people get upset from the harmless "good luck" at the start of games, I think garde might just drive someone over the edge (and we all know just how close most chess players are to the brink of insanity).
A 1380 FIDE (1529 USCF equivalent) blundered against me like this. I, 1257 FIDE (1407 USCF equivalent was in a lost position.
Kingpatzer wrote:
I don't say 'check' and never heard of 'garde' being used in chess before. From a historical standpoint this is interesting.
For OTB play your oponent has an obligation to make a legal move. If they make an illegal move because they didn't notice they were in check, there is a time penalty. That penalty can make a difference.
Saying "check" helps your opponent and does nothing for you. Aside from the point that unnecessary noise can be a disturbance to the players around you, why would you choose to help the person you're trying to crush?
Sportsmanship.
As far as I know, "garde" is actually derived from French gardez la reine, meaning "Protect (your) queen!" (gardez pronounced like "gar-DAY").
In his Chess learning book, Nezhmetdinow (Soviet chess master from Kazan) says: Saying "Check" is not mandatory, but if the opponent overlooks this and makes illegal move, you must remind her/him: "You are in check!""
I used to play with my Greek Uncle, he wouldn't say "garde" but said something like "Ah thER en" something like that for the same purpose - when a queen was being threatened - he passed recently and I cant ask him what language or what exactly the term was - does this ring a bell for anybody?
Otheren or Ah theren
Thanks.
In the 1935 horror movie „The Black Room“ (featuring Boris Karloff) they play chess and use „garde“, this is was brought me here.
Interesting how something meant to be a sign of good manners in chess is now regarded as disrespectful
I thi we tend to shrink from the notion that chess is truly a combat sport. It is no accident that the word checkmate is derived from an Arabic expression meaning the king is dead. In a friendly or informal game, if the players agree on certain rules such as saying Garde, they have every right to play that way, but in serious chess it makes no sense at all. It is a game that makes maximum demands on our attention and cognitive abilities in general, and players are responsible for how they employ these. People who hang their queen need some remedial work, not indulgence, which is not going to help them improve their game in the least. Thus what is intended to be a favor to the opponent is really no favor at all.
Fascinating post!