I seriously doubt a big company like Getty Images would risk getting sued for licencing material that is in the public domain. The WWII material that is in Getty Images (at least the material that was linked to above) is said to be material from "Archive", but no other information regarding where it was taken from is given. Copyright breach, specially with commercial intent, is severely punished in most nations (specially in the US, with hefty sums), so, as I said, I seriously Getty Images would risk breaching such rights. I would write them an e-mail asking for more information about the origin of such material, skunker.
I came across a new "meta" stock photo search engine. They are relatively new, but they seem to have a large database of photos. It may save you time from having to go to each individual stock photo site. Here is the link: http://www.stockphotofinder.com Good luck!
I need photographs of Dogs and Cats........., good looking pictures without people in them................?
Morguefile is the site I usually recommend as well. I made a list of sites 18 months ago (see Free Graphics drop down menu), but every time I need a decent picture, Morguefile seems to have one. It's good to have a short list of sites with free (and royalty-free) stock photos, though, because you're not always gonna get lucky at Morguefile (so to speak).