Born into an influential Dutch family, van Hall initially studied to become an officer in the merchant marine, but after having worked for some years as third mate he was rejected because of his eyesight. Unable to work in the merchant marine, he moved to New York City in 1929. His brother, the future mayor of Amsterdam Gijs van Hall, who already worked at a bank, helped him get a job with a Wall Street firm. Having thus been introduced to banking, van Hall returned to the Netherlands and became a banker and stockbroker.
After the Germans invaded the Netherlands in May 1940, a fund was established to help families of merchant-sailors. Van Hall was asked to help set up the Amsterdam chapter together with his brother Gijs. Because of his banking experience, van Hall was able to provide funding with the help of guarantees by the Dutch government in London. Soon thereafter, the Germans began taking anti-Jewish and forced labour measures, and resistance against these measures increased. Van Hall expanded his fund-raising activities for all kinds of resistance groups, and he became known as the banker to the resistance. One of the ways in which van Hall raised funds for the resistance was the "robbing" of De Nederlandsche Bank. With the approval of the Dutch government-in-exile, the van Halls managed to obtain as much as 50 million Dutch guilders. According to Nout Wellink, former president of the bank, this figure is comparable to a half billion Euros in 2010. Together with his brother, van Hall falsified bank bonds and exchanged them in the bank for the real bonds. With these, paper money was collected. This was done behind the back of Rost van Tonningen, president of the bank and a notorious member of the Dutch Nazi party National Socialist Movement in the Netherlands. Another way of collecting money was borrowing from wealthy Dutch people. As a proof of their investments, they received a worthless old stock, but after the war they could get their money back in exchange for the stock paper. In 1944, Walraven was the leader of the NSF ; he was also the coordinator of the Kern and the Driehoek, a cooperation of various Dutch resistance groups. The NSF supported a variety of resistance groups and underground papers like Het Parool, Trouw, and Vrij Nederland.
Nicknames
Besides being called the banker to the resistance, Walraven had various additional nicknames in the resistance movement to ensure that his real name was not exposed. For example, he was called the Olieman for his abilities to lubricate the friction between resistance groups, as well as Barends, Oom Piet, and primarily Van Tuyll.
On 27 January 1945, the meeting place was given away by a member of the resistance who had been arrested the day before and who wrongly believed the members of the meeting would know he had been arrested and would not attend the meeting. Although the Germans had a vague idea there had to be somebody who coordinated the finances for the resistance, they never found out it was van Hall. In January 1945,, a founding member of the Dutch resistance, was betrayed by the Dutch collaborator Johan van Lom. Van Vliet broke under torture and, as a result, the Germans were led to several leading members of the resistance, including van Hall.
Van Hall was posthumously awarded by the Dutch government with the Dutch Cross of Resistance. The United States awarded him with the Medal of Freedom with Gold Palm.. Israel recognized him as "Righteous Among The Nations" in 1978 for supporting and funding for between 800 and 900 Jews in hiding during the war. In honor of his deeds in the resistance, a monument was erected in the fall of 2010 near the office of the Dutch Central Bank, at the Frederiksplein 40 in Amsterdam.