Johann Heinrich Gossler (II) became a member of the city state’s council in 1821. His generation carried out all of the reforms which made it possible for Hamburg to maintain and develop its leading role as an economic and financial centre in the 19th century. The senator recognised the value of good connections to the emerging United States at an early stage. In 1828 he sent his eldest son, Johann Heinrich Gossler (III), to Boston. To make use of the connections there the latter founded together with another young German man the company Gossler & Knorre in Boston. One after the other his brothers, then his sons and nephews, joined the management of the business for a few years. Under the name Gossler & Co. and up until 1902 it played an important role, together with its branch office in New York, in the business of the Hamburg parent house.

In Boston Johann Heinrich Gossler (III) married Mary Elizabeth Bray in 1829, the grandgranddaughter of Samuel Eliot who had made himself a reputation through the independence of the United States. A year later the couple moved to Hamburg, where Johann Heinrich (III) joined the family business. After the death of his father, senator Johann Heinrich Gossler (II), in 1842 he continued together with his brother Wilhelm to lead the company, which to an ever increasing degree was developing into a banking house.