Trade in the Hanseatic city was blossoming. The increasing importance of shipping and industry was reflected in the formation of many new joint stock companies.

Joh. Berenberg, Gossler & Co. was in these years one of the founders of Hapag (1847), of North German Lloyd (1857), of Ilseder Hütte (1858), of the Norddeutsche Versicherungs AG (1857) and of the Vereinsbank in Hamburg (1856). By virtue of the activities of the bank abroad it became amongst other things a founding shareholder of the Bergens private bank in Bergen (1855), the Hongkong and Shanghai Banking Corporation HSBC (1865), Den Danske Landmandsbank in Copenhagen (1871) and the Svenska Handelsbanken Stockholm (1871).

In solidarity with his maternal grandmother’s ancestors Johann Heinrich Gossler gave his eldest son the Christian names Johann Berenberg – and he was known as John B. In 1864 John B. Gossler joined the bank as partner. The Hamburg Senate sanctioned in 1880 the change of the family name to Berenberg-Gossler.

At the time of the founding of the Reich in 1871 John B. had already been a partner of the bank for six years. In the merchant community of the Hanseatic cities of Hamburg and Bremen there were considerable reservations regarding the commercial and trade ramifications of the Reich’s foundation. This was the cause of a protracted struggle over for the customs union of Hamburg with the German Reich, which was finally completed in 1888.

In contrast to many of his peers John Berenberg-Gossler energetically championed the customs union cause, together with the planning of a free port for Hamburg. In recognition of the merit he had earned in this regard he was made a member of the Prussian nobility in 1889.

There then followed in 1910 the further ennoblement in the Prussian hereditary barony, linked with the ownership of the family estate of Niendorf which was converted into an entailed estate. Whilst in Hamburg fun was made of this ennoblement (Mayor Burchard: »A Hamburg businessman cannot be further ennobled.«) and his own family also voiced concern (John B’s sister Susanne Amsinck: »But John, our good name!«), the title was probably an advantage outside of Hamburg.

For Joh. Berenberg, Gossler & Co. the period of promoterism was very successful and around the turn of the century the house had built up an asset base which made it possible to survive the times up to the beginning of the First World War, which were full of economic and banking crises, wholly unscathed.