What is the history behind the colorful name of this result? Cartan-Eilenberg states it without any particular fanfare.



Who named it the Snake Lemma?
I suspect the name just arose naturally (for obvious reasons) but that it would be tough to trace back to any single person. After Cartan-Eilenberg proved it in 1956 (Homological Algebra, p.40) the first mention I see in English is by Tate in 1966/67 (p-divisible groups, p.178) followed by Hartshorne in 1968 (Cohomological Dimension of Algebraic Varieties, p.446), neither of which bother with a citation, reference, or quotation marks ([1](http://tinyurl.com/8h59j7o)). However, it was used a bit earlier - also without citation or quotation marks - by Begueri-Poitou in 1965 ([2](http://tinyurl.com/9aoxzl7)) as 'lemme du serpent'; mentioned early on in their abstract. [NB: the first page of the linked pdf incorrectly lists the second author's surname as Poiton.]




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**Edit:** I used [numdam](http://www.numdam.org/numdam-bin/search) to search for 'serpent'. Cartan has an unrelated [quotation](http://archive.numdam.org/ARCHIVE/SB/SB_1964-1966__9_/SB_1964-1966__9__271_0/SB_1964-1966__9__271_0.pdf) about a snake nearly biting its own tail (1965, pdf p.16/17), but actually relevant is a [paper](http://archive.numdam.org/ARCHIVE/PMIHES/PMIHES_1964__20_/PMIHES_1964__20__5_0/PMIHES_1964__20__5_0.pdf) by Grothendieck dating to 1964 mentioning a *snake diagram* ("le diagramme du serpent", pdf p.195/258) that he attributes to (Bourbaki, *Alg. comm*, chap. I, $\S$1, no 4, prop. 2). You can see the term *snake diagram* in the much later [English translation](http://books.google.com/books?id=Bb30CjGW7EAC&lpg=PA21&vq=snake&pg=PA4#v=onepage&q&f=true), and (confirmed by the comments below) it is found in the 1961 original, as well. As far as I know, this is the first published instance that uses the *snake* terminology.


**My guess for the time being:** The term *snake diagram* originated (in French) around 1961 and was first used by one of the Bourbaki members (possibly Cartan, Eilenberg, or Grothendieck). *Snake lemma* almost certainly has a similar origin.


