The town of Ostrołęka began as a fortified settlement on the Omulwia river, an estuary of the Narew River. The settlement was located in the area now known as the Old Town, or Stare Miasto, and was situated on a prominent trade route between the regions Mazovia and Prussia. Because of its location, the small settlement soon grew into a center of trade, and as early as 1373 had gained town privileges under Chełmno law, as confirmed by Siemowit III, Duke of Masovia.
More privileges were granted to the town in 1427, 1436 and 1437. Together, these privileges provided the necessary conditions for the town to grow. The privileges were extended after Masovia was incorporated into the Crown Kingdom of Poland in 1526. The newly named “Ostrołęka Crown Land” (Polish: Starostwo ostrołęckie) became the property of the queen, Bona Sforza. The town’s many farms and the forests in the surrounding area, the Kurpiowska Forests, provided basic income to the town. Products such as beer, one of the town’s most notable products, were shipped up the Narwia and Wisła rivers to Gdańsk, where they were shipped throughout Western Europe. In addition to shipping and brewing, many local people were involved in shoemaking, fishing, butchery, and the milling industry.
An outburst of wars (especially the Swedish Deluge) and epidemics in the 17th took a toll on the town. Damage from the Northern War (1702-1709) occupation by the Swedish and Russian armies led to the town’s collapse. Only in the later part of the 18th century did the town experience notable economic recovery, and trading relationships with Gdańsk, Królewiec and Warsaw resumed.
A Cavalry Brigade commanded by General Antoni Madaliński was stationed in Ostrołęka in the months preceding the outbreak of the Kościuszko Uprising. In March 1794, Madaliński refused to carry out a demobilization order and set off towards Kraków, which was the beginning of the uprising.
The town became a part of the Prussian partition after the third partition of Poland and was a part of New East Prussia in the Province of Płock. In 1807 it became part of the Duchy of Warsaw, and after 1815 the Kingdom of Poland (Russian Partition, Płock Province). On May 26, 1831 the Russian army defeated the Polish army in the battle of Ostrołęka, which was the beginning of the end of the November Uprising of 1830-31.
From 1867 onwards, the town belonged to the Łomża Government. In the late 19th century, local industry entered a period of rapid, intense growth accelerated by railway connection opened in 1893 leading to Łapy and Małkinia and onwards to Warsaw and Petersburg. Also, in the late 19th century, Russia built a series of fortification around the town to serve as a garrison on what was then the border of Russia and Prussia.
Ostrołęka suffered considerable damage during World War I, though it benefitted from an additional narrow-gauge railway connection established with Myszyniec, Kolno, and Łomża. After the war ended and Poland was reborn, the town became part of the Białystok (and, after 1938, Warsaw) province.
During World War II, after the town was incorporated into East Prussia in 1939, the Germans oversaw the mass murder of Poles and Jews. Since the town was located directly on the frontline of the war from 1944 to 1945, it again suffered serious damage.
After the war, Ostrołęka became home to a meat processing plant, a cellulose factory, a paper mill, and a heat and power plant. In 1975, the town became the seat of a new province, and after administrative reform in 1999, has continued as the center of Ostrołęka County in the Masovian Province.
- Niedziałkowska Z., Kronika najważniejszych wydarzeń z dziejów miasta Ostrołęki do 1945 roku, Ostrołęka 1989.
- Niedziałkowska Z., Ostrołęka. Dzieje miasta, Ostrołęka 2002.