In occupied Norway, goods as well as information sharing between resistance movements and the outside world, including anti-Nazi resistance in Sweden and the government-in-exile in London, was crucial. In Stockholm, there were both representatives of the Norwegian Milorg resistance group and the exiled government. The courier lines between Oslo and Stockholm were vital, but the border became increasingly controlled during the first years of the occupation.
The courier lines between Oslo and Stockholm were vital
Train lines between Oslo and Stockholm became one of the main such routes. The trains used on this route were steam locomotives, although electric trains were already common at the time, as steam trains could not be sabotaged by cutting the electricity lines.
Hiding secret information on the trains was difficult. Information was hidden on thin paper behind the destination signs and on microfilms under seats and in the bathrooms on the train, but it required someone with access to the carriages.