Brandenburg Concerto No. 5 "Brandenburg Concertos" takes a central place. Nonetheless around half a dozen of Bach's extant concertos, including some of the "Brandenburg Concertos" and lost models of his later harpsichord concertos, seem to have had their roots in his Weimar period. Most of what Bach may have left with his employer in Weimar perished in a fire destroying Schloss Weimar in the 1770s. In 1719 a new large two-manual harpsichord arrived in the residence of Bach's then-time employer at Köthen. BWV 1050a, an extant early version of the fifth "Brandenburg Concerto", may have been conceived for this instrument, but that seems unlikely
Brandenburg-Prussia broke out, with Brandenburg-Prussia involved as an ally of the Dutch Republic. This alliance was based on a treaty of 1669, and resulted in French occupation of Brandenburg-Prussian Cleves. In June 1673, Frederick William abandoned the Dutch alliance and concluded a subsidy treaty with France, who in return withdrew from Cleves. When the Holy Roman Empire declared war on France, a so-called "Reichskrieg", Brandenburg-Prussia again changed sides and joined the imperial forces. France pressured her ally Sweden to relieve her by attacking Brandenburg-Prussia from the north. Charles XI of Sweden, dependent on French subsidies, reluctantly occupied the Brandenburgian Uckermark in