I was looking through old photos and found some from my visit in the Warsaw Uprising Museum some 2 years ago. Among them are photos of the letters that people were sending during the Uprising and I thought it might be an interesting topic for mail lovers. Sorry, the photos are not of best quality.
"On 1 August 1944, the Warsaw Uprising was launched that lasted for 63 days involving the civil population, including women and children. Upon its failure, the residents were driven outside the city or placed in camps and the city was razed to the ground. The losses of the civilian population as well as Polish culture were formidable: burnt libraries and museum collections, temples and palaces. Nearly 200 thousand Warsaw residents perished and 84% of the buildings were destroyed". [source]
As soon as the fights started people organized the Scout Field Post (I hope I translated the name well) that was functioning within the limits of Warsaw during the Warsaw Uprising. The post was run by volunteers and sending letters was free of charge (although people were willingly "paying" with books, bandages and food for people in hospitals). It produced it's own stamps in 5 different colors for each of 5 districts. The post boxes with the sign "The Insurgent Post" were located in 40 points of the city. The letters were delivered by scout boys and girls. They could contain up to 25 words and were cenzored (there could be no military information in them). Daily were sent from 3 to 6 thousand letters. During the 63 days of the Uprising 200 thousand letters were delivered. It was one of the biggest organisational phenomenas during the Warsaw Uprising, functioning in extreme circumstances.
In those letter people were writing mostly about their situation, if they are alright and asking for health of their relatives and saying that they're missing them.
If you ever visit Warsaw don't miss the Warsaw Uprising Museum:) It's organised in a very interesting way, even for those that are not particularly interested in history.