Here's some more info on "No Nos Moveran". Joan Baez had refused to play in Spain as long as the Franco regime was in power. In 1977, one year after Franco's death, things were changing in Spain, and she went there to play for the first time, attracting a lot of attention from the Spanish press and public (she did have a lot of Spanish fans who were familiar with her records). As Joan always did sing a good number of Spanish language songs, it was quite easy for her to put together a song list appropriate for her audience. The Franco government had earlier censored 2 songs off her Spanish language album "Gracias a la Vida", before allowing it to be sold in Spain. One of those was "No Nos Moveran". Since Franco was now kaput, Joan naturally decided to sing the song. She chose to do it on her initial appearance in Spain which was on their most popular evening TV entertainment show, apparently watched by virtually everyone in the country. She dedicated the song to La Pasionaria, a famous female revolutionary fighter who led the Spanish Republican forces in the defense of Madrid against the Fascist forces led by Franco with the help of Hitler and Mussolini. There was no leftist hero in Spain more notorious than La Pasionaria (which means "the impassioned one"...more or less). Well, it got a huge reaction. The audience was intially stunned, then elated, and it had a profound effect throughout Spain, drawing a great deal of attention to her tour. The whole tour in fact raised a whirlwind of controversy, utterly false rumours ranging from the extraordinary to the laughable, veiled threats from rich fascists in expensive cars, confrontations with the press, you name it. Read Joan's book "And A Voice To Sing With" pages 254-263 for the complete account. A fascinating section in a truly great book.
I am just about absolutely positive that this song originated in Spain as a song of the Spanish Republican forces. That would have been in the period 1936-1938 approximately, which predates any of the suggested points of American origin in this discussion. It was then adopted by every leftist group imaginable in every common language group, appearing in numerous English versions. The English language versions tend to be a bit awkward sounding in comparison to the original Spanish words.
I lived in the USA from age 10 to 20, during the 60's, but I'm a Canadian, now back in Canada. One thing I noticed during my stay in New York State is that Americans are generally under the impression that EVERYTHING (except maybe Communism) originated in the USA. It's not their fault, that's just what their schools and media tell them from the time they are toddlers. Well, I think that in the case of "No Nos Moveran", that is not so...but I can't say for absolutely certain sure...it's just my best guess.
Anyway, thanks for the info, Joe, you have supplied the missing line I was looking for, and I now have some vague understanding of how this "thread" system or whatever you call it works. Sort of...