Most people don't know that in 1942 the German U-Boats where sinking ships within sight of the US coast. 397 ships were sunk in the first 6 months of 1942 some where even sunk inside the Gulf of Mexico. I know it's hard to see in the picture, this poster was made to stress to merchent ship crews that they were easier to find if they made smoke. It shows two rather gruff looking Germans looking for a target and they are unable to see the ships in the top frame because the ships are not making smoke, the text says "Donner und Blitzen; der convoy I see not". In the bottom frame shows the Germans finding the convoy because the smoke from the ships goes up over the horizon, the text there is "Ach, Himmel! Dere he vos!!"