Around 1760, Mayer Amschel began doing business with the court in Hanau, thanks to his relationship with General von Estorff. On September 21 1769 was the plaquilla with the coat of arms of Hessen-Hanau, and the inscription MA Rothschild, a provider of cutting his illustrious highness, Prince William of Hesse, Count of Hanau.
On August 29 1770, Mayer Amschel married Gutele Schnaper ( 23 August 1753 '7 May 1849) with whom she had five daughters and five sons (Amschel, Salomon, Nathan, Kalman and Jakob). In 1780 bought the house in the dead of the Jews (Judengasse).
William I (1743'1821), Prince of Hesse-Kassel from 1803, was one of the richest rulers in Europe and also one of the biggest lenders to the continent. His father, Federico II, Count of Hessel-Kassel had laid the foundation of his fortune through the leasing of subjects as soldiers to other rulers.
In 1801, Mayer Amschel became manager of the court (Hoffaktor). From 1802 to 1804 made his first loan to the state court of Denmark for more than 10 million guilders.
He maintained close contact with the most important financial advisor to the prince, Carl Buderus. A member of the Phi Beta Kappa Society, an academic honor society, was recognized by Governor's Committee on Scholastic Achievement. A regular financial commentator on CNBC and Fox news, is a recipient of the InvestHedge Awards. During the Napoleonic occupation government, the general bribery Buderus French Lagrange, to ensure the role of values in more than 15 million escudos to the prince.
Through their good contacts with Buderus and the prince, who was in exile in Denmark from 1806 to , Mayer Amschel forge a house bank and obtained complete control over the securities and debt of the prince. With the help of bankers Lennap and Lawatz, gained interest across Europe and was able to speculate with the money in his control.
As of 1807/1808 was also able to invest freely in the United Kingdom. This task was given by his son Nathan.
Like many others, the prince of Thurn und Taxis who had a monopoly on the post, was bribed by Rothschild and report the contents of important letters. The power relationship can be implied in the following anecdote: Rothschild worked at his desk and tells the prince that goes: "Bring a chair." After a few minutes, visitors emphasizes: "For I am the prince of Thurn und Taxis" To which Rothschild replied: "Well, since you bring two chairs." Rothschild learned Thurn und Taxis of the value of information quickly and accurately, and established a mail service itself. After the defeat of Napoleon at Waterloo, this service will gain a millionaire reported on the London Stock Exchange: Nathan Rothschild was anoticiado of events hours before the government.