"[1] Seyler was one of the first merchants and bankers from modern Germany to establish trade relations with the United States and East Asia.

Much of the company's wealth derived from their position as leading sugar importers from the Americas to the North European market, in combination with their activities as merchants bankers.

He served as a member of the French-appointed council of Hamburg and after the Napoleonic Wars as the President of the Commercial Deputation, one of the city-state's main political bodies.

His father had been born in the Swiss Canton of Basel and had come to Hamburg as a young adult, where he had established himself as a merchant banker in the 1750s and 1760s.

As a merchant banker Abel Seyler became highly controversial in Hamburg due to his "malicious" speculation in financial instruments, and in 1763 his companies went spectacularly bankrupt with enormous debts in the wake of the Amsterdam banking crisis of 1763.

Following the death of their mother in 1764, Ludwig Seyler and his brother and sister were raised in Hanover by their maternal uncle, the noted Enlightenment natural scientist J.G.R.

His sister Sophie Seyler (1762–1833) was married to the Sturm und Drang poet Johann Anton Leisewitz, the author of Julius of Taranto.

Felix Hoppe-Seyler, the principal founder of biochemistry and molecular biology, was an adopted son of his nephew.

By 1800 the capital of the company had doubled since he became a partner, to about a million Mark Banco, and had established itself as one of the largest merchant houses of Hamburg.

Astrid Petersson notes that the company's "extensive sugar imports in the period after 1814, especially from Brazil, the U.S. and East Asia, some of which represented a continuation of their trading relationships dating back to the late 18th century, contributed significantly to the company's wealth.

During the Napoleonic Wars Hamburg was occupied by France from 1806 and annexed into the Bouches-de-l'Elbe département of the First French Empire in 1811.

The Berenberg company's head office was moved to his home in Wandrahm in 1813 when the Gossler family's city residence, Mortzenhaus, was requisitioned by the French and turned into a military hospital.

In the summer of 1813 he was appointed by the French Governor-General Louis-Nicolas Davout as a member of the municipal council (conseil municipal),[8] the governing body of Hamburg which had replaced both the government (known as the council, later as the senate) and the parliament under French rule.