Working in the bank, van Hall’s first task for resisting the Nazis was to free the funds owned by the Dutch Royal Family now living in London. From there, despite having Nazis peering over his shoulder, he realised he could divert money away from the Reich and into the hands of those Dutch in most need.
The Dutch Royals entrusted van Hall with helping the families of stranded Dutch servicemen and Jewish families being persecuted or forced to hide. With the approval and connivance of the Dutch government-in-exile, he moved Dutch wealth around and out of the country. He literally robbed the Dutch National Bank on a daily basis.
He then began to finance the Dutch resistance effort.
Together with his brother, van Hall falsified bank bonds and exchanged them in the bank for the real bonds. With these, paper money was then collected. With the approval of the Dutch government-in-exile, the van Halls managed to obtain as much as 50 million Dutch guilders. He then began to finance the Dutch resistance effort.
Despite his high profile job, van Hall was also the leader of a triangular arrangement between small and competing resistance groups. Astonishingly he maintained almost absolute anonymity while providing the endless funds needed to print newspapers and propaganda. He ‘simply’ diverted funds away from the Nazi war machine.
His downfall would come eventually come in January 1945, when the resistance was betrayed by a collaborator who confessed under torture. Imprisoned and held in Haarlem, van Hall would have probably survived the war, but was executed along with other prisoners to punish an action by the resistance: an act and resistance he had personally funded.