The original sign outside the Rothschild’s shop was a red shield;
allegedly with the image of a double-headed eagle,
which would later become the emblem for Scottish Rite Freemasonry.
Many Jewish families followed the money lending (usury) tradition through Europe, since the law in many countries didn’t allow any Jew to own or make use of the land, and prejudices prevented them from finding other ocupations. Commerce and banking -despised by the Catholic faith- were interpreted as ethical by some Jews (see chapter "From the Middle Ages to the first Bankers") so they were activities that some Jewish families practiced in order to prosper.  One of these families became notorious in XVIII century Frankfurt am Main (Germany); through a small coins shop and counting house owned by an usurer named Amschel Moses Bauer. The first born of his 8 children was called Mayer Amschel Bauer; who was taught by his father all the secrets of finances, money lending and coin collection; for which he showed great aptitudes. Mayer Amschel took over the family business in 1755 after his father’s death; changing the family name to Rothschild, which corresponds to the shop’s red (Ger. “Rot”) sign (Ger. “Schild”).
In 1756 Mayer Amschel Rothschild starts working in a banking house in Hanover; owned by another Jewish family named Oppenheimer (best known in modern times for one of its member's -Robert “destroyer of worlds” Oppenheimer- role as director of the Manhattan Project, which developed the first nuclear bomb during WWII ). Through his work with the Oppenheimer family, Mayer comes in contact with general von Estorff. Von Estorff introduces Mayer to the court of Prince William I of Hesse-Hanau; one of the richest royal houses in Europe. Mayer incremented considerably his family fortune by working as a financier for Prince William I; where he discovered that lending to governments is far more profitable and secure than lending to ordinary people. His duties also included hiring the Hessian soldiers to foreign nations on behalf of William I, and also realised how profitable wars are by witnessing how the Hesse fortune grew above that of other royal houses in Europe.
However, back in those days, wealth did not give a man rights or social status.  We saw already that Jews were not allowed to own or make use of lands, and we also saw that the Church despised and condemned usury. It was during those times, when a movement among Jewish intellectuals emerged in Germany. This movement pursued the eradication of the monarchy and the church [both also in the way of Rothschild's interests], and infiltrated or created secret societies to achieve those goals by any means.
... Next chapter: the American Revolution
Wikipedia: Familia Rothschild (http://es.wikipedia.org/wiki/Rothschild)
 Herbert Lottman (1927-Nueva York)
 Wikipedia: Robert Oppenheimer (http://es.wikipedia.org/wiki/Robert_Oppenheimer)