Greg Hanegraaf’s WWII fighter plane scrapbook (1941-43)
Explanation re: saving cooking fat: the primary purpose of the grease (fat from cooking), at least as advertised, was to make glycerine (glycerol), which is produced when fats are heated with strong bases like lye (the other product is soap, which I presume they also found a use for). The glycerine was used to make nitroglycerine, which was used in explosives (most notably dynamite) and gunpowder (old-fashioned black powder, made from charcoal, sulfur, and potassium nitrate, was already a thing of the past; most smokeless powders of the time used high explosive like nitroglycerine cut with other ingredients to slow the detonation and make a propellant). I’ve seen ads from the period that explicitly told housewives their old cooking grease would be made into bombs and gunpowder.