The diary of Gustav Otto Stenbock from the Royal Prussia campaign in autumn 1656 and the account of the battle of Filipów (22.10.1656) are in the Riksarkivet archive in Stockholm. They have not yet been used in the study of the Polish-Swedish War of 1655–1660. In many places, correlating with the relevant fragment of the work of Samuel Pufendorf on the wars of Charles X Gustav, they introduce new details: the chronology of the initial phase of the Stenbock campaign and the composition of the division led by the Lithuanian field marshal Wincenty Gosiewski. In the latter case, it is not certain whether the list concerns the battle of Prostki (8.10.1656) or Filipów. The bases of the edition were copies from the Swedish Microfilms collection at the Central Archives of Historical Records in Warsaw.