The Action Gum card series was released by Goudey Gum Co. in about 1938 or '39. It contained 96 cards and no stickers. The American Card Catalog reference for this series is R1.
The card fronts depicted watercolor artwork depicting contemporary warfare using all of the weapons and technology available to armies of that era; the pre-war date of the series is suggested by the fact that none of the cards showed specific real-world events. The pictures were surrounded by a white border with no captions.
Card backs gave the card title and set number at the top, followed by a block of text narrating the action. Below that in bold letters was the set title, ACTION GUM, followed by the tagline 'The Greatest Card Series Ever Produced'. At the bottom was the name of the manufacturer and the mention of a few more of their gum-related products.
Action Gum is a popular set due to its subject matter, scarcity, and antiquity, and is thus sought after and a bit pricey.
Oddly, the publisher's name is misspelled as 'Goudy' on several of the card backs.
A Canadian version of this set featured 60 cards from the series, renamed Action Series; they are easily identified by (among other things) the bilingual English/French text on the card backs.