The German security services had many ways of uncovering their opponents in the Resistance. Some of their organizations were, in fact, highly professional and adept at counter-espionage in its many manifestations. Some of them relied on brute force. But they, like resisters, also sometimes benefited from sheer luck.

We can take Dutch-Paris operations in Brussels as an example. In July 1943, the Committee rented an apartment on the rue du Trône as a sort of office or headquarters for their daily work of hiding Dutch fugitives or helping them to get to Spain or Switzerland. In late December, the Committee moved the escape-line portion of the work across town to a pension on the rue Franklin.

The German Sicherheitsdienst raided the pension on rue Franklin in late February 1944, where they captured six Dutch resisters, the Belgian landlady and ten aviators. The Germans knew the address because they had captured a Dutch-Paris courier in Paris two weeks earlier. She had escorted some Jews from the Netherlands to Paris on their way to Switzerland, stopping at the rue Franklin on their way. She gave her German interrogators that address along with many others.

The Germans didn’t trouble the rue du Trône when they raided the rue Franklin. The courier arrested in Paris didn’t know about it and none of the men arrested in Belgium appear to have mentioned it to their interrogators. Maybe the Germans didn’t realize that they had found more than just an escape-line at the rue Franklin.

But the Sicherheitsdienst did raid the rue du Trône at the end of March 1944. It looks like the Germans put two and two together to find the second half of the Dutch-Paris operation in Brussels, but the two raids had nothing to do with each other. During one of their usual document checks on the streets, the Germans had arrested a man who had received help at the rue du Trône. “In his terror [angst]” as the Committee’s later report put it, the man betrayed the address.  The resisters in charge of social work escaped the raid but had to leave the country.   The Committee then reorganized the way they distributed money and false documents to those they were hiding and weathered the last harrowing weeks before the liberation in September 1944 without further arrests.

Sometimes it all hung on whether a man turned to the left or to the right.  One way it was good luck for the Germans and bad luck for the resisters.  If he turned the other way, or stopped to nurse a cup of ersatz coffee at a café, or fell into a long argument with the man selling newspapers and missed the document check, it was good luck for the resisters.  Neither they nor anyone else would ever know it, though.