Two more sieges followed in 1640 and 1641. The town needed several years to recover. One reason for the new boost was the creation of a merchant society 1658, which secured Hirschberg's position as the most important center of linen and veil trade in the Silesian mountains during the 17th and 18th centuries. The Protestants of the city were oppressed during the Counter-Reformation, but the second Treaty of Altranstädt, which allowed a Protestant community center and church to be established outside the medieval city walls, brought relief. Great sacrifices by the merchant society, especially its most prominent member Christian Menzel, made the construction of a large church, modelled after Church of Catherine in Stockholm, possible. The cemetery of the church was the preferred burial place for most merchant families. Hirschberg was annexed with Lower Silesia by the Kingdom of Prussia during the Silesian Wars. The city was again partly destroyed, had to pay contributions and was seized several times. The detachment from Austria and the new border in the mountains to the south badly damaged the economy as the merchants lost a large part of their customers. Although Prussia took on substantial efforts to revive the economy, they never recovered completely and finally lost their position during the industrial revolution. In 1800, John Quincy Adams, ambassador in Berlin at that time and future President of the United States, visited Hirschberg and said: "Nothing can be more beautiful than the location of Hirschberg, a beautifully built city with numerous splendid buildings, in a valley surrounded by hills on all sides, with the magnificent view of the Giant Mountains (Karkonosze/Riesengebirge Mountains)". In 1871 the town became part of the German Empire with the Prussian-led unification of Germany, as one of the largest towns in the Province of Silesia. In 1889 the "Deutsche Riesengebirgsverein" (German Giant Mountains Club), an organization to protect the environment of the Giant Mountains (Krkonoše) and to promote tourism, was founded by Theodor Donat and 47 other dignitaries of the region. After World War I, the town became part of the Prussian Province of Lower Silesia in 1919, and in 1922 became a separate city. During the Nazi era under the regime of Adolf Hitler, a subcamp of KZ Gross-Rosen was located in Hirschberg. On September 1, 1939, the day of the German invasion of Poland and the outbreak of World War II, Luftwaffe used the airport in Hirschberg to conduct air raids on Poland.