Here's one more from my post-holiday mailbox stash.
Prior to WWI, Germany had a colony in Kiauchau (Kiautschou), China. At the outbreak of war, the Japanese captured the colony, and shipped the German POWs back to prison camps in Japan.
These are two postcards sent from Coln, Germany, to a prisoner in the Nagoya POW camp. They have some really nice censor cancels, and I'm working on trying to translate.