Jacobus Kann became an active and passionate Zionist after visiting the First Zionist Congress in Basel in 1897 and became one of Theodor Herzl’s most loyal aides.
In 1899 Kann, together with Dutch Chief Rabbi Joseph Dunner founded the Dutch Zionist Organisation and in 1902 he became the first leader of the Jewish National Fund in the Netherlands.
When other leading Jewish bankers, like the Rothschilds, refused to cooperate with Herzl in creating the necessary financial institutions for the Zionist enterprise it was Kann who helped Herzl and Wolffsohn set up these institutions to support the Jewish settlers in Palestine. He was co-founder of the Jewish Colonial Trust (JCT) in 1899 and served on its board for 30 years. One of the subsidiaries of the JCT was the Anglo Palestine Company (APC), now Bank Leumi, which was founded in 1902 with involvement of Kann who also served on the board of directors of the APC.
The first chairman of the Bank’s Board of Directors was David Wolffsohn, Herzl’s successor as the leader of the Zionist Movement. Its first General Manager was Zalman David Levontin.
After Herzl’s death in 1904, the Inner Action Committee (Engeres Actions-Comité), the Executive Committee of the Zionist movement ruling from Cologne, Germany, consisted of Wolffsohn together with Kann and professor Otto Warburg. Kann held this position until 1911.
During this period, in 1905, Levontin visited Kann in The Hague and received the notarized power of attorney and funds to buy land in Palestine. With this mandate the land of Keren Jebali was bought on which the members of the Ahuzat Bait housing association started building their homes in 1909.
In 1907 Kann visits Palestine and he publishes a book the year after: Erets Israel, The Jewish land. In Dutch but also translated in German and French (in 1909 and 1910). In the book he writes what every Zionist dreams but what no one dares to say out loud: an autonomous Jewish state has to be created. It caused quite a stir, especially within the Zionist movement, because it could upset the relationship with the Ottoman rulers.
The clash between practical and political zionists reached it peak in the period that Kann was in Inner Action Committee. Criticism from the “practicals”, leads to the resignation of Kann and Wolffsohn in 1911. Just before leaving Kann suffered a heart attack. Kann kept a lot of influence in later periods because he, together with early sympathizers of Herzl, continued to rule the financial institutions.
WWI almost disconnected the Zionist leaders from each other in the different belligerent countries. Kann, as a citizen of a neutral country, was able to continue their communication by acting as their mail man and also took care of mediation by the Dutch government in remittances to the Jews in Palestine.
When the JNF had to move during WWI it was Kann who took care of its business from The Hague. It was in this period that the Americans became an important actor for the Zionist Movement. Because of the war in Europe, income from traditional donors decreased but was more than compensated by the US. Louis Brandeis, who was president of the American Zionists during WWI and increased its membership tenfold, was able to create mass support from US Jewry, but also the US government. In 1919 he wrote to his wife” the task of steering the Zionist ship is not an easy one. Fortunately on financial matters I find in Dutch safe leadership “, most probably meaning Kann, who handled much of the Zionists financial affairs.