They are definitely military stamps.
The first stamp is shown on this Danish site, which says that they were issued from 1929 - 1963:http://www.asfe.dk/pop-up1.asp?stampid=10923
"Faltpost" means field post.
From what seems a very useful reference site that lists a huge number of stamp inscriptions:
"SVARSMARKE and SVERIGE = Sweden - military letter reply stamp - A stamp printed on the back of envelopes given regularly to military servicemen. The reply stamp would be cut out of the envelope and pay postage to any armed forces serviceman."
I think the other "stamp" is in fact from a printed envelope for military post. However, the site is in Swedish which I don't understand:http://www.smps.se/area/military_covers.php
A similar "stamp" is on this cover:http://www.asfe.dk/pop-up1.asp?stampid=429
Anyone out there understand Swedish?