Ss Rex was built in 1931 and was sunk in 1944 Ww2.  Sunk during an allied bombing raid by allied forces off the coast of Italy.

For reference I've included in the listing pics taken during this bombing raid (not included). 

Great history to read online about this ship. 

Image measures 3.5x11".  I have this listed as a photograph but actually appears to be a post card.