Polish–Lithuanian Commonwealth Navy

At the turn of the seventeenth century, Poland became ruled by the House of Vasa, and was involved in a series of wars with Sweden (see also dominium maris baltici).

[1] During the reign of Sigismund III, the most celebrated victory of the Commonwealth Navy under command of Admiral Arend Dickmann took place at the Battle of Oliwa in 1627 against Sweden, during the Polish-Swedish War.

[1][3] This provocated a minor Polish intervention in the Thirty Years' War to help Spanish Netherlands against Denmark–Norway, England and Dutch Republic (planning to open a new front on the Eighty Years' War), in exchange for a promised Habsburg Spain's help against Sweden (agreeing that the Poles would then take over the Flanders navy and receive Spanish technical advice to their naval industry).

The Polish ships, sent to Wismar, were much better equipped than the imperial ones, being Król Dawid their flagship, and even frightened Gustavus Adolphus of its potential if Wallenstein added his ships under construction or developed another separate Spanish Baltic Fleet, but some unforeseen problems arose as the Polish-Lithuanian crews refused to sail unless they were paid in advance, as many were river peasants (Kashubians and Flisacos of Vistula) who were used to plundering the coasts that the Swedes blocked, but the expedition to Wismar seemed useless and incomprehensible to them.

Also, internal conflicts of interests and leadership between Spain, Holy Roman Emperor, Catholic League and Wallenstein, as the effects of the Spanish Bankrupt of 1627, prevented this Spanish-Polish fleet from having any relevant operations, being relegated to fighting the Danish and Swedish fleets in very small sporadic skirmishes, and their mission lost part of his proposal after Peace of Lübeck on 22 May 1629 (when Denmark quits from the War), as Spain wasn't really interested to fight against Swedes for Poland, just to divert the Dutch army in helping Danes in Germany while diverting forces at Belgium, and also get German ground military aid from Catholic League to fight in Netherlands or Italy against Dutch and France in exchange for Spanish support against Denmark (Spanish aid to Poland was conditioned on maintaining Danish conflict in Baltic Sea or avoiding Swedish intervention to Germany, so Austrian Habsburg would be free to help Spain by land).

[1] The 58th article signed and sworn by king Władysław IV Pacta conventa announced creation of a war fleet "according to needs of Commonwealth".

The Harbor in Puck was too shallow for the biggest ships and the usage of Wisłoujście (a fortress near Gdansk) was constantly plagued by difficulties from the Danzig Patricians (afraid that a king with a strong naval arm would step upon their "liberties", control tolls, exert taxes etc.).

They were quite impressive and raised in record time (finished in 1634, consisting of strong wooden (oak) palisades, earthen walls, trenches and moats).

[4] Their main goal was to plague Swedish communication and supply lines near Piława (now Baltiysk in Kaliningrad Oblast) and on Zatoka Wiślana (Vistula Bay).

There were plans to use Cossacks in their light but very fast boats against Inflanty (Livonia) and even to raid the Swedish shore (to burn, pillage, capture merchant ships etc.).