(1688-1740, known as the "Soldier King" - German: Soldatenkönig) King in Prussia and elector of Brandenburg from 1713 until his death in 1740, as well as prince of Neuchâtel. He was succeeded by his son, Frederick the Great.
Letter signed, four pages (on two conjoined sheets - both sides), 8 x 10,75 inch, with calligraphic letterhead, Berlin, 26.02.1713, in old German, to a cousin - Frederick William I of Prussia announces the "sorrowful" (translated) death of his father, Frederick I (11 July 1657-25 February 1713), and the accession of power, signed by Frederick William I of Prussia in black ink, with intersecting letter folds, and scattered mild signs of age wear - in fine condition.
"nach ausgestandener schwerer Leibesschwachheit gestrigen Tages - um 1 Uhr nachmittags, durch ein sanftes und stilles Ende, aus diesem mühseeligen und jammervollen [...] in das ewige Freudenleben"
"after suffering severe physical weakness yesterday - at 1 o'clock in the afternoon, through a gentle and quiet end, from this laborious and miserable [...] into eternal joy"
He also confirms the wish that the friendship with the cousin, which already existed with the deceased father, will now be continued and intensified.