In 1896 Friedrich Bienemann jr published a collection of documents concerning the siege of Dorpat (Tartu) in 1656. Among them are a series of letters from Governor Lars Fleming to Magnus Gabriel de la Gardie, the Governor General of Livonia. They are dated 3 April, 14 May, 28 May, 28 May, 8 June, 18 June, 9 July, 15 July, 28 July, 27 October and 10 November. Rainer Fagerlund mentions a few others: Fleming to de la Gardie 4 June, 21 June and 11 July. To this list of letters in Stockholm and Riga can be added the following, preserved among the Malmberg papers in Uppsala University Library: Fleming to de la Gardie 25 June, 19 July and 23 July. In the first of these Fleming reports that many peasants have run away and are plundering the estates of the nobility. He also reports problems with the guns - some are without carriages. In the letter dated 19 July Fleming gives details about the approaching Russians. They had crossed the border during the night between the 15th and 16th. Some units had headed directly for Neuhausen. If Neuhausen fell, Fleming wrote, the enemy would soon attack Dorpat. Reinforcements were urgently needed. In the last of the three letters, dated 23 July, Governor Fleming informs de la Gardie that he has not received any recent reports from Neuhausen. In a hastily written note at the end of the letter he writes that a detachment of cavalry just had returned. They had seem many fires in the direction of Neuhausen. The castle was supposedly still holding (apparently incorrect), because the enemy had not yet been able to bring up the heavy guns.
Uppsala University Library, Dorpat-Rigasamlingen, vol. 2 and 3 (subsequently rearranged and renamed Livonica)
Briefe und Aktenstücke zur Geschichte der Verteidigung und Kapitulation Dorpats 1656 // Mittheilungen aus der livländischen Geschichte. - 16:2. - Riga, 1896. P. 515-606
Fagerlund, Rainer, Kriget i Östersjöprovinserna 1655-1661. - Stockholm, 1979