Johann Ernst
Born: 25th December 1695, Weimar, Germany
Died: 1st August 1715, Frankfurt, Germany
Nationality: German
Johann Ernst of Saxe-Weimar (German: Johann Ernst von Sachsen-Weimar) was a German prince, son by his second marriage of Johann Ernst III, Duke of Saxe-Weimar. Despite his early death he is remembered as a collector and commissioner of music and as a composer, some of whose concertos were arranged for harpsichord or organ by Johann Sebastian Bach, who was court organist in Weimar at the time.
Read more at https://en.wikipedia.org/wiki/Prince_Johann_Ernst_of_Saxe-Weimar