From the The Finnish Defence Forces comes the Finnish Wartime Photograph Archive, a collection of 160,000 photographs taken during World War II when Finland fought to free itself from Nazi Germany and the Soviet Union. Preserved in their original state, the pictures "portray life on the home front, ruins from bombings, the war industry and events that happened behind the front lines." As you can imagine, some of the photos can be disturbing.
On a brighter note, let me add this. You can download each and every photo, and use them for educational purposes. The archive only asks that you give proper attribution by mentioning "SA-kuva" as the source. And, indeed, "SA-kuva" should be given credit for the image above.
You can enter the complete archive here.