Johann Sebastian Bach
Bach visited the court of King Frederick II of Prussia
Potsdam, Prussia (Present Day Germany)
In May 1747, Bach visited the court of King Frederick II of Prussia in Potsdam. The king played a theme for Bach and challenged him to improvise a fugue based on his theme. Bach obliged, playing a three-part fugue on one of Frederick's fortepianos, which was a new type of instrument at the time. Upon his return to Leipzig he composed a set of fugues and canons, and a trio sonata, based on the Thema Regium (theme of the king).