Espionage, starring the secret agent character Black X, was originally created for the half reprint half original Quality Comics title Feature Funnies in late 1938 in issue #13. It ran as a 4 page strip in Feature Funnies until issue #20 whereas the title changed to Feature Comics and the series continued until issue #22. After that, the strip began appearing in Smash Comics starting with the first issue in August of 1939. The stories were expanded in length to 9 pages. Eisner's involvement with the character as an artist came to an end with the 13th issue of Smash Comics in 1940 with an August cover date. At that point he was hard at work on The Spirit series which debuted in newspapers on June 2, 1940.
Below are two Espionage stories that have all of the hallmarks of Eisner's early work, fast paced action, dynamic perspective, strong female characters, inventive design and layouts, his deft touch with a brush and his wonderful use of shadows. The only thing missing is an overt sense of humor, which is a key ingredient that made The Spirit wartime adventures so fun.
Smash Comics #4 November 1939