The Dutch government-in-exile in London had a problem that is today almost inconceivable: they didn’t know what was going on in the Netherlands. Nor did they have a way to communicate with the people they claimed to represent. They had to resort to clandestine means.

One such was to microfilm reports and instructions and then mail them to Switzerland, Sweden or Spain hidden in the bindings of obscure academic books. Following instructions telegrammed from London, the military attaché in, say, Bern would go to a particular Swiss bookseller and order a history of Javanese politics published in 1869 or a treatise on translating Sanskrit into Frisian. When it arrived he would slit open the cover and forward the microfilm on to London or the Netherlands.

The microfilms could also be sent by courier who carried them across the borders in fountain pens, hairbrushes, flashlights and the like. Dutch-Paris provided such a courier service for General van Tricht and Dominee Visser ‘t Hooft in Switzerland. The general trafficked in military intelligence, the pastor in civilian information.

In theory, at least, Dutch-Paris kept the information line separate from the escape line. Four couriers, including John Weidner, spent years crisscrossing France and Belgium to “loan” an acquaintance a fountain pen or flashlight in cafés in Brussels and Toulouse. In practice, the lines merged.

For instance, Dutch-Paris couriers did not regularly climb the Pyrenees to deliver microfilms to the Dutch consulate in Barcelona. They gave Engelandvaarders who were about to cross the mountains as part of their journey to England the “objects” with instructions to deliver them to the consul.

But any Spanish, Swiss, French, Belgian or Dutch customs agent or police officer with an eye for suspicious travelers, not to mention Germans, could wreck the delivery by confiscating the “object” and/or arresting the courier. The Spanish, for instance, routinely seized flashlights and razors. Engelandvaarders were instructed to try to mail them to the consul in Barcelona before turning themselves in to the Guardia Civil.

The men waiting for the microfilms in Bern, Madrid and London had some particularly anxious weeks in February and March 1944 when they were trying to establish a new code for telegrams between Bern and Madrid. Part of the code was sent via an agent who worked for Dutch intelligence in Madrid and who hurt his back in the mountains. He arrived, but only after several weeks’ delay. Madrid sent the other part via a French agent who was supposed to hand it over to John Weidner in Paris. The French courier was arrested and Weidner disappeared after the apparently unrelated arrest of his sister in Paris. It turned out that Weidner’s other sister took the codes to Bern, but gave them to the pastor rather than the general.

Then in May the French pro-Nazi Milice arrested Weidner in Toulouse because he looked like a communist on the most-wanted list. Weidner got away by jumping out the prison window, but the Milice got some of the microfilms he had been carrying.

This was too much for our man in Madrid. He proposed a new channel of communication after it became possible to send food packages from Spain to Switzerland. First he removed the top of a can of sardines and thoroughly washed it out. Then he soldered on a false bottom covering microfilms and declared it ready to mail. He sent four tins of Spanish sardines to London so they could prepare their own.

But he thought this up in July 1944, just before the liberation of southern France when more normal means of communication opened up behind the Allied lines. So the sardines never got the chance to serve in Her Majesty’s secret service.

Engelandvaarders were Dutch men and women who made a clandestine journey to England in order to join the Allied militaries or serve the Dutch government-in-exile.