Polish–Swedish War (1626–1629)

The Polish–Swedish War of 1626–1629 was the fourth stage (after 1600–1611, 1617–1618, and 1620–1625) in a series of conflicts between Sweden and Poland fought in the 17th century. It began in 1626 and ended four years later with the Truce of Altmark and later at Stuhmsdorf with the Treaty of Stuhmsdorf.

Despite the Commonwealth winning certain notable battles, the Swedes would end up victorious in the end.

1626
The first encounter of the war took place near Wallhof, Latvia, where a Swedish army of 4,900 men under Gustavus II Adolphus ambushed a Polish-Lithuanian force of 7,000 men under Jan Stanisław Sapieha. Polish-Lithuanian casualties amounted to between 1000 dead, wounded and 150 captured. The Lithuanian commander later suffered a nervous breakdown.

In May 1626 King Gustavus Adolphus launched his invasion of Polish Prussia. Escorted by a fleet of over 125 ships, Swedish forces numbering over 8,000 soldiers (including 1,000 cavalry) disembarked in Ducal Prussia near Piława (Pillau). The landings were a complete surprise to the Polish–Lithuanian Commonwealth's defences, and despite his relatively small forces, Gustavus Adolphus quickly captured 16 Prussian towns, almost without a fight (with the neutral Duchy of Prussia's passive support). Many of these towns were inhabited by Protestants and they opened their gates freely to the Lutheran Swedish forces, who they saw as co-religionists. The Swedish king, however, failed to capture the largest prize - the city of Danzig (Gdańsk), which maintained its own small army and fleet for defence. In preparation for his major attack on Danzig, King Gustavus Adolphus increased his forces to over 22,000. The Polish king, Sigismund III, received no support from his vassal Ducal Prussia when fighting to defend it. He deployed north with an army of 11,000 men and pitched battle at Gniew against King Gustavus Adolphus' force of 8,150 infantry, 1,750 cavalry and 74 cannon. The fighting continued for several days - from 22 September to 1 October 1626 - until Sigismund III withdrew his army, and called on reinforcements from around the country.

The Polish hetman (historical army rank equivalent to field marshal) Stanisław Koniecpolski quickly came to his king's aid with a force of 4,200 light cavalry, 1,000 dragoons, and 1,000 infantry. In early November the king handed him command of the army. With further reinforcements Koniecpolski soon had 10,000 men to match the 20,000 Swedish troops in Prussia. Engaging in a war of maneuver - small mobile units striking at the enemy's lines of communication - Hetman Koniecpolski managed to halt any further Swedish advances, even forcing the Swedes onto the defensive.

In the meantime, the Sejm (Commonwealth Parliament) agreed to raise funds for the war, but the situation of the Polish forces was difficult. Lithuanian forces were dealt a serious defeat in December 1626 near Kokenhusen in Livonia and retreated behind the Dvina river.

1627
Hetman Koniecpolski recaptured the town of Puck on 2 April 1627. The Swedes planned to strike at Koniecpolski from two directions — Oxenstierna from direction of the Vistula and Johann Streiff von Lauenstein and Maximilian Teuffel from Swedish-held Pomerania. The flooding of the Vistula disrupted their plans and allowed Koniecpolski to intercept the enemy units coming from neighboring Pomerania. In mid-April, Koniecpolski (with 2,150 hussars, 3,290 cossack cavalry, 2,515 western infantry, 1,620 Polish infantry, 1,265 dragoons and 2,000 Ukrainian Cossacks) surrounded a Swedish force inside the town of Czarne (Hammerstein).Three days later the Swedes surrendered, leaving behind their banners and standards. Many of the Swedish troops, who were predominantly newly raised German mercenaries, changed sides to the Commonwealth. This victory also convinced George William, Elector of Brandenburg, to declare his support for King Sigismund III.

During the night of May 22 to 23, King Gustavus Adolphus was lightly wounded while attempting a night-crossing of the River Vistula in a boat near (Kieżmark), south of Danzig (Gdańsk), and had to retreat. In July he led a force to lift the siege of Braniewo, and lay siege to Orneta (Wormditt). Hetman Koniecpolski responded with the sudden attack and capture of Gniew. Gustavus Adolphus was reported to have been impressed by the speed of Koniecpolski's reaction. Later at the Battle of Dirschau (modern Tczew), Koniecpolski with about 7,800 men (including 2,500 cavalry and hussars), tried to stop the Swedish army (10,000 men including 5,000 infantry) from reaching Danzig. A major battle was fought between 17 and 18 August 1627 (in the new style calendar), with the Swedish forces positioned near the marshes of the River Motława. The Swedes hoped to provoke the Poles into a reckless attack and then to destroy them with infantry fire and artillery, but Koniecpolski decided otherwise. The Swedes then took the initiative and attacked with cavalry, and managed to deal severe damage to the Polish cavalry, but failed to inflict a crippling blow on the main body of the army (the morale of which remained high, mostly thanks to Koniecpolski). When, King Gustavus Adolphus was shot in the shoulder by a Polish sniper, the Swedes decided to end the assault and withdrew from the field, reportedly in good order.

Stanislaw Koniecpolski decided to take the war to the seas and gathered a small Polish–Lithuanian Commonwealth Navy of 9 ships, mostly with aid from the City of Danzig. He defeated a Swedish flotilla on 27 or 28 November 1627 (in the New Style calendar), at the battle of Oliwa near Danzig.

Over the winter, Koniecpolski recognised the need to reform the Polish army, especially to strengthen the firepower of his infantry and artillery to match the Swedish units. The Swedes, for their part, learned from the Poles how to best employ their cavalry by using more aggressive tactics.

1628
In 1628 the Polish forces, lacking funding, were forced to stop their offensive and switch to defense. Swedish forces captured the towns of Nowy and Brodnica. Hetman Koniecpolski counterattacked by using his small forces most efficiently — fast cavalry melee attacks combined with the supporting fire of infantry and artillery, and using fortifications and terrain advantage. By that time the war had become a war of maneuver, with neither side willing to face the other without advantages of terrain or fortifications. It was a miserable year for Swedish occupying garrison troops, with epidemics wiping out huge numbers of men and horses.

1629
On 2 February, while King Gustavus Adolphus was wintering in Sweden and Hetman Koniecpolski was away in Warsaw, the Polish forces were badly defeated at the Battle of Górzno, where a Swedish force under Field Marshal Herman Wrangel encountered a Polish army under Stanisław Potocki. The Poles suffered 1,500 dead and wounded plus 500 captured; the Swedes lost only 30 dead and 60 wounded. Hearing of the defeat, the Polish Sejm was persuaded to increase funds for the army and accepted military aid from the Holy Roman Empire in the form of a corps of imperial troops under Field Marshal Hans Georg von Arnim-Boitzenburg. Another imperial corps, commanded by Albrecht von Wallenstein, operated in nearby Pomerania. Nonetheless, Koniecpolski was forced to withdraw from several strategic strongholds in Polish Prussia: in time he managed to recapture the seaport of Putzig (now Puck).

The Swedish king returned to Polish Prussia with substantial reinforcements in May, and marched south towards Graudenz (Grudziądz) hoping to cut-off Arnim's newly arrived imperial corps before it could join Koniecpolski. He was unsuccessful, and while withdrawing north towards Swedish garrisons in Stuhm (Sztum) and Marienburg (Malbork) he was drawn into battle on 27 June 1629 at Honigfeld(t) or Honigfelde near Stuhm, in an action known to the Poles as the Battle of Trzciana. In this encounter, while attempting to cover the withdrawal of his infantry, Swedish cavalry were subjected to a series of fierce engagements at the villages of Honigfeldt, Straszewo and Pułkowice. With the aid of Arnim's heavy cuirassiers the Poles with their faster 'winged' hussars and cossack mercenaries were able to gain a great advantage over the light Swedish horsemen. Swedish losses in the fight were heavy, amounting to 600 or 700 killed, almost all of which were cavalry (including Herman Wrangel's son). The Polish took 300 prisoners, 10-15 standards, as well as 10 of Gustavus Adolphus' famous leather cannon. Commonwealth losses were under 300 killed and wounded. The Swedish king himself barely escaped with his life and later said he had never taken "such a hot bath".

Truce of Altmark
The war in Prussia demonstrated that the armies of the Commonwealth were poorly prepared for warfare requiring the continuous use or fighting of field fortification elements. To a large extent, this neglect was due to the nature of the wars conducted by the Commonwealth in the eastern borderlands in the last century, characterised by the poor quality of fortifications, where the main importance in the vast spaces was given to moving cavalry rather than infantry and artillery. It was not until the wars with Sweden, and especially the operations in Prussia, where the country was relatively densely dotted with towns that could provide an operational base for the operations, that the shortcomings in the quantity of artillery and the amount and training of infantry were highlighted. An army that was better able to construct and capture field fortifications had better control over the conquered area. Koniecpolski's ad hoc reforms could not in a short time make up for the neglect in this area since the time of Batory. The state, which had been at war on many fronts for a long time, showed serious financial shortcomings, which were greatly exacerbated by the blockade of Polish ports by the Swedish navy. Without a reform of the army and the state's finances, defeating the thoroughly reformed Swedish army was impossible at this point. To do so, a longer respite was needed - and this could only be provided by peace, or at least a truce of several years.

Mediation between the warring parties was undertaken by the Netherlands, who were very interested in freeing Baltic trade from the ongoing war. Gustavus Adolphus was also keen to end the fighting in Prussia, as he was in a hurry to join the battles being fought in Germany and assist the Protestant camp, which was experiencing serious difficulties following the defeat of King Christian IV of Denmark at Wallachia. France and England were also interested in involving Sweden in the fight against the Habsburgs. Brandenburg diplomacy acted similarly. In addition to the financial difficulties of the state, the envoys of the Polish-Lithuanian Commonwealth were also prompted to the truce by the worrying actions of Moscow, which had established contacts with Turkey and purchased a very large amount of modern armaments, especially muskets, in Western Europe. In addition, Tartar incursions intensified, which, however, were successfully repelled by regimental officer Stefan Chmielecki.

After long negotiations, a truce was finally concluded at Stary Targ on 6 September 1629, to be valid for six years. Tolkmicko, Elbląg, Braniewo, Piława and Klaipėda remained in Swedish hands. The Brandenburg Elector, who played an ambiguous role in the ongoing war, George William (who let Swedish troops advancing on Pomerania through his territory), was given Sztum, Głowa and Malbork as a sequestration on the basis of a truce treaty (the Elector undertook to surrender these cities and the surrounding area to the Swedes if no lasting peace was reached after the expiry of the truce). In Livonia, the previous state of possession was retained. The Commonwealth had to pay half a million zlotys for Austrian assistance. Soon after the truce was concluded, some Crown troops, with the knowledge of King Sigismund III, marched to Germany to support the Catholic side.

A major success for Sweden was to gain the right to levy a duty on Polish sea trade of 3.5% of the value of the goods transported. The finances obtained from this were mostly used for the war in Germany. Only there did the reformed Swedish army demonstrate its worth to the whole of Europe, gaining a reputation as the best army in the world and elevating Sweden to the status of a mighty power. The Swedish successes in Germany also explained why the then still mighty Commonwealth had such difficulty in defeating Gustavus Adolphus's army.

The war, fought at the mouth of the Vistula, wreaked havoc in Gdansk Pomerania and Ducal Prussia. A plague that swept through these areas and even reached Mazovia also added to the misery. As a result of the suspension of maritime exports, the Polish economy lost 30 million zlotys, according to Jan Seredyka's calculations. In Royal Prussia, war damage covered a third of the countryside. Gdańsk's trade and textile industry also suffered serious losses.

Treaty of Stuhmsdorf
The six-year truce had already ended after the death of Sigismund III. The Commonwealth and its army more than regained the prestige lost at Altmark with impressive victories over two great powers, Russia and Turkey. Meanwhile, Sweden, three years after the death of Gustavus Adolphus and with the terrible defeat at Nördlingen fresh in its memory, was at a crisis point and ready to avoid another conflict at all costs. The new ruler of the Polish-Lithuanian Commonwealth, buoyed up by his impressive victory over the Russian army at Smolensk, wanted to consolidate his military fame, so he did not wish for any agreement at all. However, it was not on him that further developments depended, but on the attitude of the Sejm, and society was already decidedly tired of the constant wars fought by the Republic in the 17th century. Thus, only Wladyslaw IV sought war - the nobility, the magnates and Gdansk wanted peace.

A strong asset for Polish deputies in the peace negotiations with the Swedes was the 21,000-strong crown army concentrated in Pomerania in the summer. Finally, on 12 September 1635, King Wladysław IV Vasa was forced to conclude another truce with Sweden in Sztumska Wieś, this time for a period of 26 years. Under the terms of the treaty, the Swedes were to abandon all strongholds in Pomerania and Ducal Prussia and cease collecting customs duties from Polish ports. In Inflants, both sides remained in possession, but the Swedes were to allow Catholics religious freedoms in the part they occupied. In addition, Lithuania was to have full freedom of trade on the Dvina River. King Wladyslaw IV of Poland suspended his claim to the Swedish crown for the duration of the truce (i.e. until he was to reach the age of 66).