1. Letter from Duke William to Duke Frederick. Udrennen/Ūdrande, 23 June 1601. LVVA, Collection 1100, Inventory 13, Collection 719, Volume I.

In the letter, William explains why he cannot come to the assistance of his brother with 50 cavalrymen: two Swedish warships were still present near the coast at Windau/Ventspils. News had also been received that the Swedes intended to attack Windau/Ventspils with a large fleet. A message had come from the castle commander of Kandau/Kandava that a couple of hundred Swedes had attacked the coast. Cannon-fire had knocked off the chimney of the manor-house at Angern/Engure; Plönen/ Plieņciems and Kösterzeem/Ķesterciems had been ransacked; the peasants had fled into the forest and there was a shortage of men for defence. William also complains that the nobles were not properly discharging their services as vassals and that he had only 100 cavalry at his disposal.

2. Letter from Charles IX of Sweden to Christian II, Elector of Saxony. Erebro, 7 April 1606. LVVA, Collection 1100, Inventory 13, File 719, Volume I.

Replying to a letter from the elector of 26 December, urging him to spare the Duchy of Courland, because in fighting against the Swedes the Courlanders were only fulfilling their obligation as vassals, the king declares that this is impossible and that the duchy represents a threat to his state. Charles states that he has repeatedly written to the dukes to refrain from hostile actions against the Swedes, but his warning has not been heeded. Christian forwarded the king's letter to Courland.

3. Christian II, Elector of Saxony (1583–1611).

4. List of damage done by the Lithuanian army. Wallhof/Valle-Manor, 26 January 1622. Excerpt. LVVA, Collection 554, Inventory 1, File 124.

In the course of the war the Duchy of Courland suffered damage caused not only by the Swedes, but also by the forces of the feudal overlord of Courland, the King of Poland. Manors located near the main roads suffered the most. One of these was the Wallhof/Valle, where in January 1622 representatives of the duke and the Lithuanians carried out an inspection of the damage. For example, peasant Jacob Baldon had lost 5 horses, 2 cows, 6 sheep, some grain and 1 cauldron, while peasant Pladdon had lost 3 horses, 2 cows, 1 hog, grain and oats.

5. Letter from Landhofmeister Mathias von der Recke to Duke Friedrich. Jaunpils, 12/22 April 1622. LVVA, Collection 554, Inventory 1, File 89.

Recke reports that the peasants of manors Autz/Auce, Schwarden/Zvārde, Doblen/Dobele and Ihlen/Īle had assembled and killed more than 50 Poles. About 30 bodies had been buried, some thrown into the bog, and some had had stones tied around their necks and had been drowned in Autzensee/Lake Auce. Since this would be impossible to hush up, Recke advises that the duke should first send someone to the Polish court with complaints about the violence perpetrated by the soldiers. That the peasants had defended themselves against the Poles, who were raping their wives and daughters, and perpetrating other atrocities, could be fully justified. Recke adds that he has just learned that the people killed were not from the Polish army camp, but roaming robbers and merchants from Lithuania.

6. List of damage suffered by the peasants of Grünhof/Zaļenieki-Manor. Compiled in 1625. Excerpt. LVVA, Collection 554, Inventory 1, File 124.

In autumn 1625 the Lithuanians led by Christoph Radziwiłł set up camp near Eckau/Iecava. The local population supplied the army with food, but this did not save them from marauding by the soldiers. The victims included peasants from Grünhof/Zaļenieki, for example, peasant Kugeru Jēkabs was robbed of 8 cows, 2 bulls, 5 horses, 5 sheep and 8 pigs etc., the damage totalling 1420 marks. At the time, a good horse cost 100–200 marks.

7. A soldier of the early 17th century. Drawing in the memorial album of Johann Hieronymus Rörscheidt. LVVA, Collection 5759, Inventory 2, File 1403.

In the early 17th century, the armies of Europe still consisted largely of pikemen.

8. View of the Battle of Kirchholm/Salaspils. Painting by Pieter Snayers (1592–1667). Painted in 1619 after eyewitness accounts. In a private collection in France.

• indicates the cavalry of the Duchy of Courland.

On 17/27 September 1605 the army of Charles IX of Sweden fought the forces commanded by Jan Karol Chodkiewicz, Hetman of Lithuania on the bank of the river Düna/Daugava at Kirchholm/Salaspils. Although the Swedish forces outnumbered the Lithuanians almost three times, it was the Lithuanians who prevailed in this battle, one of the largest in the war. A very important role in this victory was played by the three cavalry units led by Duke Frederick (300 to 400 men), which crossed the Düna/ Daugava over the ford just before the battle commenced. The Courlander Engelbrecht Vietinghof saved the life of Hetman Chodkiewicz, and the owner of Neuenburg/Jaunpils, Matthias von der Recke, almost captured the King of Sweden, who only just managed to break away, leaving Recke his sword and helmet as trophies. The Swedes lost more than 9000 men in the battle (almost all of their infantry), while the Poles suffered fewer fatalities, with a greater number of wounded men. Of the Courlanders, only four men fell. In addition to the cavalry of the duchy, slightly under a hundred soldiers from Pilten, serving as vassals, also took part in the battle.

9. The garrison of Selburg/Sēlpils during the siege of the castle. 1625. LVVA, Collection 554, Inventory 3, File 734.

According to the list, in the summer of 1625 the castle garrison consisted of 20 men, including a mason, a shoemaker and a beekeeper. One of the soldiers was shot by the Swedes.

10. The agreement on the surrender of Selburg/Sēlpils Castle. 18 July 1625 (old style). LVVA, Collection 554, Inventory 3, File 734.

After a truce lasting almost three years, warfare between the Poles and Swedes broke out again in the middle of 1625. Gustav II Adolf of Sweden, having arrived with a large army, first took Kokenhusen/Koknese and then surrounded Selburg/Sēlpils. The castle was surrendered on 18/28 July after negotiations lasting a few hours. The accord or surrender agreement was signed by Axel Oxenstierna, Chancellor of Sweden. The residents of the castle were permitted to leave within three days with all their property, but the castle furnishings, munitions and provisions were kept by the Swedes.

11. Selburg/Sēlpils Castle. Engraving from the early 18th century. LVVA, Collection 1100, Inventory 13, File 976.

The engraving shows Selburg/Sēlpils Castle shortly before it was blown up, in 1704, but the appearance of the castle had not changed significantly since the first third of the 17th century.

12. Letter by Gotthard von der Tinnen, Supreme Captain of Selburg/Sēlpils, to Duke Frederick. Riga, 16 August 1625. LVVA, Collection 554, Inventory 3, File 734.

Tinnen explains that he is forced to surrender to the Swedes, because, together with the people from the surrounding area who have fled to the castle, he has only about 30 fighting men at his disposal. He considers it his achievement that in the surrender negotiations he has managed to secure the release of the castle residents. A few days before the arrival of the Swedes, the senior castellan had complained to the duke that he was short of money for hiring soldiers, and that the food stocks in the castle were being damaged by mice and rats.

13. Promise of loyalty by the residents of Mitau/Jelgava Castle to the King of Sweden. Draft. October 1621. LVVA, Collection 554, Inventory 1, File 124.

After the capture of Mitau/Jelgava Castle on 3/13 October 1621, Gustav II Adolf of Sweden announced that after their voluntary submission, he would guarantee the residents of Mitau/Jelgava their privileges and security, but asked in return an oath of allegiance. With the help of the king's secretary as an intermediary, the town citizens managed to delay the oath of allegiance by half a year. Instead, they had to give a written promise that they would not assist the Poles in any way. The residents of Semigallia who wished to spend the winter behind the walls of Mitau/Jelgava Castle also had to give the promise.

14. Oath of loyalty of the citizens of town Mitau/Jelgava to Duke Frederick. 5 July 1623. LVVA, Collection 554, Inventory 3, File 733.

In June 1623, on the order of Duke Frederick, a separate investigation was begun into the actions of the citizens of Mitau/Jelgava during the time of the Swedish attack. On 4 July the town citizens were implicated as being partly to blame for the loss of the castle, for which they deserved harsh punishment. However, in order to foster the development of the town, the duke retained all its rights and privileges, only ordering the confiscation of houses whose owners had moved to the territory under Swedish control. The next day the town citizens renewed their oath of loyalty to Duke Frederick, in which they promised, among other things, to defend the castle against the enemy without sparing their lives.

15. Agreement on the surrender of Mitau/Jelgava Castle. LVVA, Collection 581, Inventory 11, File 1. 23 September 1625 (old style).

After the surrender of Selburg/Sēlpils, Gustav II Adolf took castle of Bauske/Bauska, and on 21 September/1 October he reached Mitau/Jelgava. This time the defenders of the castle put up opposition, but were clearly outnumbered by the Swedes. On 23 September/3 October a surrender agreement or accord was concluded. The Swedes allowed the garrison and the other defenders to leave with their possessions and the flag flying, i.e. with honour, but the property of the duke once again became a trophy.

16. The defences of Mitau/Jelgava Castle. Circa 1625. Military Archives of Sweden, Stockholm.

In the late 16th or early 17th century Mitau/Jelgava Castle was surrounded by earthen banks and four bastions of various sizes. At the time of the Swedish attack they were in very poor condition.

17. The conditions set by the King of Sweden for recognition of the neutrality of the Duchy of Courland, and the opinion of the duke. 1625. Excerpt. LVVA, Collection 554, Inventory 3, File 383.

The protracted war forced Duke Frederick to look for ways to protect the duchy. On the one hand, he strove to arrange truce negotiations between the Swedes and the Poles, and on the other hand he tried to obtain for Courland the status of a neutral state. The duke was continually sending delegates to the commanders of the warring armies and to both kings. The Swedes presented a series of demands in return for recognising the neutrality of the duchy: the army was to be permitted free movement, the duke was not to allow the Poles into the fortresses that still remained, Polish military camps were not to be established in the duchy, the Swedes were to have free use of the Courland ports and these conditions were to be recognised by the King of Poland. Frederick declared that he could open the Sēlpils road for free movement by both armies and demanded that the Swedes return the castles of Bauske/ Bauske, Mitau/Jelgava and Tuckum/Tukums, which they had seized, offered to open up the ports to free trade, but not to military landings, and promised to obtain the agreement of the King of Poland at the next sitting of the Sejm.

18. Assurance from the Swedish commander Major Honorio Werdelet. Bauske/Bauska Castle, 25 September 1627. LVVA, Collection 554, Inventory 1, File 154.

Duke Frederick had achieved an agreement with Leo Sapieha, Grand Hetman of Lithuania, and the Swedish military leader Jacob de la Gardie that the Swedes would not attack the Polish-Lithuanian forces from the castles of Bauske/Bauska and Mitau/ Jelgava, and the Poles would not attack the castles and would break off the siege of Bauske/Bauska. Major Werdelet promised to observe this agreement, and not to attack merchants travelling from Lithuania to the Polish military camp. Even though the warring sides gave repeated assurances that they would observe the neutrality of Courland, these often remained unfulfilled.

19. A cavalryman in armour. 1600. Drawing in the memorial album of Johann Hieronymus Rörscheidt. LVVA, Collection 5759, Inventory 2, File 1403.

The text above the drawing states: “It is sweet to die for the Fatherland”. However, it is doubtful whether the inhabitants of the duchy would have agreed…

20. Order from Swedish military leader Jacob de la Gardie. Riga, 11 August 1626. LVVA, Collection 1100, Inventory 13, File 719, Volume II.

Private individuals could try to protect their property by obtaining ‘safeguard letters’ (Salvegarde Brief) from army commanders. At the request of Jürgen Düsterloe, owner of Pixtern/Pikstere-Manor, De la Gardie issued him such a letter, prohibiting the Swedish officers and men from doing any damage to Düsterloe’s manor or his peasants.