Among the many autograph letters by Furtwängler available on online sales sites, there's one that strikes a nerve among us Furtwänglerologists. It is dated March 29, 1915, and addressed to the director of the Blüthner Orchester, from Lübeck, where Furtwängler was the conductor of the Verein for a few more weeks.
This very independent ensemble from Berlin, founded in 1907 and merged with the Berlin Symphony in 1925, had a very adventurous programming strategy involving young conductors and soloists. Eugène Ormandy performed there at the age of 18, and Edgar Varèse premiered one of his first works.
In the letter, Furtwängler mentions the invoice he received from the Orchestra (which he no longer finds) for the hiring of extra musicians, and ends the message with the request to kindly express to the musicians his gratitude and satisfaction for the concert...
Which concert? The lists documenting the conductor's activity from 1906 to 1954 place Furtwängler's first appearance in Berlin on December 14, 1917, conducting the Philharmonic. However, the terms of this letter are explicit: he conducted a concert in March, or even February, more than two years earlier, leading the Blüthner Orchester.
Can anyone give us some information?

