Looking at the development of defense equipment Gdansk from the fourteenth and fifteenth centuries, that is, when the Gdańsk because of its commercial importance began to become one of the most important elements of the economy, and thus the political Polish critical importance was to build a fortress in Wisłoujściu. Steady increase in the importance of this point for the defense of Gdansk dating from its inception, which relate to at least the second half of the fourteenth century, when the site where today stands the powerful defensive team maintained, installed wooden blockhouse guarding the mouth of the Vistula River to the Sea Baltic. Since then also the importance of this team will be shaped in terms of three basic functions. The first is a shield against the actions of directed against him from the sea, and so before the artillery and desantowymi operations navies operating in the Gulf of Gdansk. In this respect, Wisloujscie played a special role during the Napoleonic wars, and Swedish. With Wisłoujściu Gdańsk was never surprised by the sea. The second function was to secure the connection with the outside world. Role Wisloujscie increased in this respect with the development of economic importance as a major port of Gdansk Poland. Full, effective blockade of the city was impossible without mastering the mouth of the river. The third was to create the so-called "head of Danzig", a castle in Grabina and fortifications in Kiezmark wide foreground, hindering direct enemy of attack and forcing it to dissipate forces in multiple directions. The usefulness of the system in this respect, especially the war showed the Stefan Batory Gdansk and Swedish wars. Thanks to its strengthening military Wisloujscie were constantly expanded and modernized. In 1562 in place of the old wooden three-storey wreath built fortification, then supplemented with additional dungeons and palisade. The next stage of expansion coincided with the turn of the sixteenth and seventeenth centuries. The fort was built by the Italian design school again. The next step in the expansion and modernization of the fortress has been done in the 1624-1626, purse is heaped brick rampart protecting the natural slope. This was in close connection with the development of the artillery for the walls not covered with a thick layer of earth ceased to be a sufficient barrier. For the first time fortress decisively influenced the course of military operations during the war between Danzig and the Polish in 1577. The role they played in Wisloujscie 1577 years it has occurred several times in Polish history. So it was during the Swedish wars and during the collapse of the Polish state in the eighteenth century, when in 1734 Gdańsk was the only one in the territory of a complex socio - political able to resist Member possessive. Wisloujscie then became, as intended, the basis for the actions of French landings walking with the aid of besieged in Gdansk by King Stanislaw Leszczynski Russians. In the years 1806-1807 Gdańsk with Wisloujscie not serve again on the Polish. Wisloujscie output becomes the basis for the Russian - Prussian attempts to come to the rescue of the city besieged by the French - Polish forces of Marshal Lefebvre. Wisloujscie fortifications and a string of up holmium become the main subject of fierce fighting - Polish-French attack and defense Prussian as to maintain or gain that would decide the fate of the city dependent on outside help. May 15 comes out of the south Wisloujscie great Prussian-Russian attack, repulsed by the Polish-French forces. Wisloujscie fortress played a major role in 1813 during the siege closed in by the Russian army Polish-French crew, commanded by General Rapp. This time, the role of the fort lies in the fact, in order to prevent the use by besieging the huge opportunities that gave them a decisive advantage at sea. Fortress in Wisłoujściu be so to those places and objects in Gdansk, which should be inspected, but that the frequently viewed unfortunately not belong. In the nineteenth century acted as a fortress prison, located in the interwar period there sailing club. In 1974, the team was a division of Fortress Wisloujscie Gdańsk History Museum. As one of only two (along with the fortress of Baltijsk) sea fortress on the southern coast of the Baltic Sea, and due to its historical value hit the World Monuments Watch list of one hundred most endangered sites on the world. Fortress Wisloujscie is not only an invaluable monument of architecture of fortification, but also one of the few largest bat hibernacula Pomorskie.