This post is only to let you know what are the two oldest baseball cards published in Spain. They are a couple of pictures included in the set "Deportes" with 100 cards of different sports. #10 and #82 are devoted to Base-Ball.
As baseball wasn't really, in the 20's, a played sport in Spain, these pictures are a kind of misterious. Probably a little bunch of fanatics played between them everytime they wanted, and I'm almost sure that the pictures are from Spanish origin. Anyway if somebody thinks the opposite, I'd be glad to know his or her opinion.
#10 reads "Detalle interesante" (Interesting detail)
#82 reads "Momento de una jugada" (Moment of a play)
The backs can be found with different advertisers, the set was published in some year of the 20's decade by Tipografía Litografía F. Domingo and they sizes 8'5 cms. x 6'2 cms.
Here the two cards:
https://drive.google.com/file/d/1BeE...ew?usp=sharing