Paper shortages in war time make for incredibly interesting philatelic objects. In 1918, when Latvia declared its independence, they had very little paper available to them for making their own postage stamps. After all, how can you truly be a country without your own stamps? What they did have was a large surplus of outdated German maps, and so, used the backs of those to print their stamps. I love them. You can read all about them here, with lots of different printings and perforations. They even made some envelopes from the maps, much like the Confederate "adversity covers" we talked about previously.