Another group of small lakes is situated in the basin of the Warta (north part of Kalisz), the largest being Goplo, 18 m.
The Lodz manufacturing district, the Polish Birmingham, is becoming more German than Polish; and throughout the governments west of the Vistula German immigration is going on at a steadily increasing rate, especially in the governments of Plock, Kalisz, Piotrkow and Warsaw.
The principal fairs are held at Warsaw (wool, hemp, hops), Lcczyca in Kalisz, Skaryszew in Radom, Ciechanoviec in Lomza, and Lowicz in Warsaw.
The privileges conferred upon the magnates of which these councils were composed, especially upon the magnates of Little Poland, who brought the Jagiellos to the throne, directed their policy, and grew rich upon their liberality, revolted the less favoured szlachta, or gentry, who, towards the end of the 14th century, combined for mutual defence in their sejmiki, or local diets, of which originally there were five, three in Great Poland, one in Little Poland and one in Posen-Kalisz.'
Hostilities had already begun with the occupation of Diinaburg (Dvinsk) in Polish Livonia by the Swedes (July 1, 1655), and the Polish army encamped among the marshes of the Netze concluded a convention (July 25) whereby the palatinates of Posen and Kalisz placed themselves under the protection of the Swedish king.