The Brandenburg Concertos were a failed audition

The Brandenburg Concertos, a collection of six suites that make up one of Bach's most well-known works, were almost a footnote to his career. Bach realized in 1720 that his status at the Köthen court was at risk since Prince Leopold's new bride reportedly did not enjoy his music. However, since he had just met Margrave of Brandenburg Christian Ludwig, he had hoped to convince him to hire him.

Bach assembled some previously-written work and sent it to Christian Ludwig, apparently to demonstrate his abilities. Ludwig, unfortunately, never answered.

By March 24, 1721, all six Brandenburg concertos had been completed. It has been argued that Bach took the prince's gamba player's technical shortcomings into consideration when writing the sixth concerto. Because he preferred to be "in the middle of the harmony," Bach chose to play the viola. For events like the prince's birthday and others, he also composed a few cantatas. When the Brandenburg Concertos (1721) manuscript was being transferred by train to Prussia for preservation under the supervision of a librarian, it almost got lost during World War II. The librarian narrowly escaped the train to a neighboring woodland when it was being attacked from above while keeping the scores covered under his coat.