The Thirty Years’ War, fought from 1618 to 1648, seriously hindered the city’s development. The increasing wartime burdens imposed on the population and troops passing through the city caused destruction; food shortages, high prices and rising taxes followed.
As early as 1619, a head tax known as the personal tax was introduced, and it was decreed that every twentieth man in the city should report for military service.
In 1690 (9 March), King Frederick I arrived in the city and stayed in Bolesławiec for some time.
At the same time, the city was burdened with wartime costs amounting to 16,030 thalers for billeting troops. In July of that year, Cossack cavalry commanded by Voivode Radziwiłł was stationed in the city; King Zygmunt III Waza had sent it to Bohemia to aid Emperor Ferdinand.
The fourth year of the Thirty Years’ War, 1622, and the increase in taxes led to uprisings among the residents of nearby villages, who refused to pay taxes and contributions. They broke out in Łąka, Kraśnik, Tomaszów and Oleszna.
The billeted troops brought disease and caused panic among the civilian population. The municipal council was forced to build barracks on the outskirts for the sick and to light warning signal fires. The epidemic claimed 640 lives that year. The city also had to provide the army with provisions costing 2,044 thalers and two combat wagons; from 15 November, a 200-man army company was billeted in the city for four days. Information about more than 400 soldiers being billeted for the entire winter dates from 1627. The city fell into debt, and special enforcement units even appeared. In 1629, the city was forced to repay its debt to the billeted troops—in beer.
The Catholic camp’s advantage in the Thirty Years’ War manifested itself in repression directed against Protestants. In 1630, under Frederick II’s edict of restriction, the Protestant Municipal Council was dismissed and sentenced to exile from the city together with its families. It was replaced by a new Catholic council. The final misfortune to befall the city during the war was the entry of Swedish troops in 1639. The Swedes reintroduced Protestant services, and their several-year stay in the city caused enormous destruction.
In 1642, the city burned down. The urban buildings were destroyed. General Torstenson forced the residents to dismantle the burned castle. The result of this destructive activity was that only around 80 residents remained in the city. Of the 25 potters, only three remained. The Thirty Years’ War ended in 1648. The city continued to feel the effects of the war for many years.