Interesting Postcard, postally used- Al Schacht 1946
 

I don't know if this is Al's signature or not. I assume it is but you should assume it isn't :) . Neat postcard either way. And I am not really sure what is meant by the word "free" where the stamp should be but maybe if it was militarily related it was free to send, as it was only a year after the war was over.
$185 delivered.

http://luckeycards.com/spcunc1946schacht.jpg

Troops on active service were allowed to send mail free. They just had to write their ID and "free" in place of the stamp.

I'm not sure exactly when it ended after WWII for all troops, but it went on for some time. Some areas like combat areas they can still send mail free, but mail sent from bases outside combat areas they have to pay the postage.