Card front (blank back)
This simple 21-card set came out a year after the A's move to Oakland. I assume it's numbered by uniform, with #5 visible on Joe's jersey. (The Yankees also retired it in his honor.)
DiMaggio spent 3 bittersweet years in the US Army during WWII, achieving a rank of staff sergeant but never coming close to actual combat. I can't say enough good things about Gary Bedingfield's site Baseball in Wartime and his profile of Joe includes a ton of great photos and info.
Value: This is a pretty obscure issue, but individual cards aren't particularly expensive. This DiMaggio cost around $20 on eBay, by far his cheapest card from an in-uniform year. (Reggie Jackson also has a rookie card in this set, which almost certainly costs more.)
Fakes / reprints: This is an easy set to reproduce, being black-and-white and on common card stock. It's unfortunately not an easy issue to authenticate--other than by its innate obscurity--so buy only from reputable dealers. (My eBay purchase included some provenance-checking.)