Swiss soldier stamps, are they postage stamps?
I found the answer in the Dutch Monthly Magazine for Philately (yes, that's what our flagship magazine, Philately, was called back then), in the April issue of 1940. A beautiful answer!


The stamps have no postage validity and are therefore not to be regarded as postage stamps in the strict sense of the word. Field post in Switzerland is postage-free. However, the field post does indeed stamp the letters sent by the soldiers.


Sometimes this stamp is placed on a 'soldier's seal', sometimes next to it. We are currently unaware whether there are regulations regarding the placement of the stamp. However, it appears to occur quite frequently that the stamp is placed next to the seal.
This reinforces the opinion of those who claim that the soldiers' stamps are intended solely to fleece the public. We, however, are of the opinion that everything connected with the postal service belongs to philately, and thus also these stamps, which we would like to place in the category of 'private mail'. Just as in earlier wars, when soldiers' stamps were issued in various countries, including Switzerland (one need only think of the internment stamps in this country), these stamps ought to receive our attention. They are signs of the times, signs of current events, and therefore we philatelists ought to examine these matters seriously, that is, critically. Do you remember? It was April 1940 when this was written. Beautiful, isn't it?

In my opinion, these soldier stamps belong in the same category as the Dutch internment stamps from 1916 and the German Field Post/Inselpost stamps from 1942-1944. Certainly collectible. In all cases, such a stamp on a letter is of course a precious item (and very pricey). Learned something new today. Thanks, Cees!
The first Swiss Soldiers' Stamps were issued privately in June 1915 (with permission from the Swiss Post Office). They were designed by soldiers who had to guard the border during the two World Wars and were "bored to death" (Switzerland was neutral). The designers' regimental numbers are often visible on the stamps. The stamps were given to the soldiers of the respective units as a memento. In 1916, the soldier's stamp took on the character of a kind of "surcharge stamp." The stamps were sold for the benefit of the soldiers' regimental coffers, making it possible to do something extra. The stamps could be affixed to letters, but otherwise meant nothing. I therefore disagree with the notion that these stamps can be equated with internment stamps. They are more like sealing stamps, or "goodwill stamps," that belong in the category of Cinderellas. Because a policeman is sometimes depicted on them, I also have a few in my collection.
Hi Willem, did you get my card yet?
Very B
but still not my ordered stamps…!!!
Nonsense is on its way