The family is believed to have originated from Płock and then moved to the villages of Ossowa, now called Osowa Krzeczanowska, Osowa Łaszewska, and Osowa Drobińska in Mazowieckie region of Poland where they worked for the senate. Once a nobleman was chosen to be an official by the king “Przywilej koszycki”, he had a job for a lifetime. He could not be recalled unless he was convicted of high treason. If he agreed, he could be moved to another, usually higher place in the hierarchy.
It is said that in the war with Prussia, King Boleslaw Krzywousty (1102-1139), with the help of a bowman, name Dołęga defeated the Prussians resulting with their leader being killed. This enabled the dismayed people of Poland to rise up with success to then attack. As a reward, Dołęga received the arrow to its coat of arms Pobog, and the new coat of arms was named after him. The Dołęga clan was famous the precision of their bowmen and the bravery of their Polish Cavalry.
In the 15th century some family members obtain some more land and built the settlement of Osowa Sień, near Wschowa and also built the customary village church of St. Fabian and St.Sebastian. Mikolaj Dołęga-Ossowski was deputy district judge (podsędek ziemski) of Wschowa (1517-?). In 1540 Mikolaj founded the original church St. Jadwigi in Debowa Leka and in 1560 , his son Piotr Poznań district writer (pisarz ziemski), next heir of village, the church returned “innowiercom”. In one of the walls a Renaissance Tomb of Bishop Albert Ossowski from 1572 can be seen.
During the 16th and 17th centuries some of the Dołęga clan emigrated to Vilna (Vilnius, Lithuania). The nobility title was renewed in Lithuania in 1674 by John III Sobieski, King of the Polish-Lithuanian Commonwealth from 1674 to 1696.When West Prussia came back to Prussia in the year 1774, the family high nobility status was recognised by the King Frederick II of Prussia (The Large One, 1740-1786). In Poland the title was renewed again in 1825 and 1850 to Mieczysław Dołęga-Ossowski.
Jan Dołęga-Ossowski was a member of the Ossowski szlachta family and is believed to be the originator of this noble family. He was somehow connected to John Ossowski of Szczecin-Osów, who himself received recognition from the King Louis I of Hungary for providing food and water to the army when it arrived at his territory in 1374. Komes Dołęga-Ossowski also owned a manor house in the village of Szczecin-Osów and was a member of the Polish Order of the Virtuti Militari. The family reached the heights of its importance during the Polish-Lithuanian Commonwealth (1569-1795).
Members of the szlachta families had the personal obligation to defend the country with men from their own towns and villages. The basic tactical unit of the army was a Choragiew, that is a group of approximately 200 men financed by a noble clan. The Choragiew fought separately and included all the necessary detachments, including own kitchen, tabors and servants.
The Dołęga-Ossowski Officers (Rotmistrz) who supplied themselves and men for the following battles were:-