Shortly afterwards, however, he moved to Paris, which appeared to offer more promising commercial prospects. However, by 1806, he was back in Berlin where, between October 1806 and December 1808, matters were complicated by French military occupation of the city. Meanwhile Humblot's friend, Carl Friedrich Wilhelm Duncker, was running the publishing business built up by Heinrich Frölich. Frölich had recruited Duncker as an assistant and then, just six weeks later, died suddenly in March 1806. Duncker spent the next two years returning the business to solvency, despite the unwavering opposition of Frölich's widow. In 1808, Duncker persuaded his former employer's widow to sell him the business. To do this, he needed a partner, presumably for financial reasons. On 1 January 1809, Duncker and Humblot acquired the business, agreeing to share profits and losses on an equal basis. The business was renamed , which is the name under which it continues to trade (2018).