The inscription on the reverse side is translated like this:
Comrade! Do you know what Knäckebrot is?
Knäckebrot is a whole-grain bread containing elements that you cannot refuse.
Knäckebrot is the Foundation of your body and makes you resistant to diseases.
Knäckebrot reduces thirst, so should be in your bag on the March, during exercise and fighting.
Knäckebrot is a valuable addition to army bread.
So, Comrade, evenly distributed Knäckebrot every day.
Original pack of Knäckebrot: