Hi gosd, I'll give this a shot since no-one else has. Trouble is I'm not on my games PC so this is from memory.
Under the countries section up near the beginning of the campaign.xml file, there are instructions for each nation, giving the urls/addresses for the location of the images to be used in certain events in the campaign (eg victory, death). I assume the urls point to the Uires file, where I assume the relevant images are located, perhaps under the Uires/campaign folder?
So if you looked at the USA country section in a functioning campaign, and compared the urls provided with those in the DR_italy_1943 campaign, you should be able to work out what the correct syntax is. You will need to rootle through the Uires folder to find the location of the images, or simply copy the image over from another install if you cannot find a suitable image.
HTH,
D