One of the chapters in volume 2 of Karl XII på slagfältet (1918) deals with the crossing of the Düna (Daugava) in July 1701. A surprising number of the footnotes refers to either Nordberg's Konung Carl den XII:tes historia (1740) or Adlerfelt's Histoire Militaire (1740). This indicates that major battles during the GNW have not necessarily left a big contemporary paper trail, i.e. that we would probably not have had a great deal more information about the Swedish planning for the battle of Poltava even if a lot of documents had not been burned before the army surrendered a couple of days later.
However, in the case of the Düna crossing there still exists quite a few items which to my knowledge have not been used before. On 5 July 1701 Captain Peter Andersson Preen, commander of the ship Wachtmeister, informs Erik Dahlbergh that he has received orders to collect as many boats he can find. Preen tells Dahlbergh that few are available as the Saxons are preventing all merchant ships from passing Dünamünde (LVVA, fond 7349, op. 1, vol. 275). Quite a few items are in LVVA, fond 7349, op. 1, vol. 316, which contains letters from Swedish commanders of detachments and redoubts in the neighbourhood of Riga. They report on Saxon movements and fortifications as well as about possible locations for a crossing. As the date of the crossing draws nearer there also appears reports of the gathering of boats (Jacob Johan Staël von Holstein, dated Wetsack 6 July) and finally the news of the success and the Saxon retreat (Staël von Holstein, dated Wetsack 9 July at 11 am).