Keyboard concertos by Johann Sebastian Bach soloists, were all adapted into harpsichord concertos by the composer, BWV 1058, 1054 and 1062 respectively. It is often assumed that Bach's extant violin concertos were written in his Köthen period (1717–1723): it can however not be proven from documentary evidence that any of them existed prior to around 1730. In September 1725 Bach performed organ music, accompanied by other instruments, in Dresden. The works he performed there have not been identified. More than a year later he composed several cantatas with an organ obligato part. Several movements of such cantatas were derived from earlier lost concertos, and resurfaced in
Brandenburg Navy Brandenburg Navy had almost thirty active warships. These ships were used primarily to secure control over hostile trade routes and maritime trading, as blockades and to provide naval defence, and to also provide reinforcement on various military operations, which would frequently involve engagements with unfriendly warships. In 1682, Frederick William, the prince-elector of Brandenburg, who was intensely involved in the navy's affairs, secured the navy a base at Greetsiel, but they shifted to Emden a year later. Frederick William died in 1688, and his descendants took no interest in the Brandenburg Navy. Frederick III and his grandson Frederick the Great