Otto II's raid on Poland

Otto II's raid on Poland was a military expedition against Civitas Schinesghe the state of Mieszko I after Mieszko I supported the rebellious prince Henry the Quarrelsome during the civil war in Germany following the death of Emperor Otto I the Great. The invasion ended in defeat for the Holy Roman Empire, as Otto II could not achieve any military success which forced him to return to Germany.

Background
The initial ruler of the Piast state, Mieszko I, historically regarded as a loyal ally and even a friend of Emperor Otto I the Great, saw a sudden rift in relations in 972. This rupture occurred when Margrave Odo, an administrator of the German frontier, independently invaded Piast territories.

In response, Mieszko engaged Odo's forces at the Battle of Cedynia in 972 and emerged victorious. Despite its minor scale, the clash caught the attention of the emperor. Mieszko faced condemnation for spilling the blood of German knights, prompting Otto I to demand a punitive measure. He ordered Mieszko's six-year-old son and heir, Bolesław, to be sent to the imperial court as a hostage. Though Mieszko complied initially, Bolesław's stay in Germany was brief. Upon the emperor's death in 973, Mieszko seized the opportunity to secure his release, leveraging chaos in Germany. Subsequently, Mieszko became entangled in a German civil war, supporting a rebellious duke against the rightful heir, Otto II.

Following the quashing of the rebellion, Otto II sought to assert his authority. He imprisoned Henry of Bavaria, the rebellion's leader, and initiated punitive measures against his allies. Additionally, Otto II launched military campaigns against the Bohemians, who had supported the rebellion.

In the midst of these events, Mieszko's Christian wife, Dobrawa, passed away in 977, severing ties between the Piasts and the Bohemians. This allowed Mieszko to pursue alliances with German nobles, aiming to reconcile with the emperor.

Meanwhile, King Lothair of France unexpectedly allied with the Piasts, further complicating Otto II's situation. Lothair's invasion of Aachen, a significant fortress, diverted German attention from Mieszko's actions.

Raid
As Otto II prepared to march east in 979, Mieszko fortified his positions in Greater Poland, notably strengthening the fortress of Poznań.

The subsequent conflict between Otto II and Mieszko remains shrouded in mystery, but it set the stage for future confrontations between the German and Polish rulers. Ultimately, faced with logistical challenges and diminishing morale, Otto II retreated from Greater Poland without achieving decisive victory. The conflict forced Otto II to recognize Mieszko's strengthened position and seek a peace agreement, albeit indirectly and without admitting defeat.

Aftermath
The Polish-German agreement was concluded in the spring or possibly summer of 980, because in November of that year Otto II left his country and went to Italy. It appears that during this time Mieszko I married Oda, daughter of Dietrich of Haldensleben, Margrave of the Northern March, after abducting her from the monastery of Kalbe. Chronicler Thietmar described the event as follows: "When Bolesław's mother died his father married, without permission from the Church, a nun from the monastery in Kalbe, daughter of Margrave Dietrich. Oda was her name and her guilt was great. For she scorned her vows to God, and gave preference to the man of war before him (...). But because of the concern for the well-being of the homeland and the necessity to secure its peace, the event caused no break of relations, instead a proper way was found to restore concord. For thanks to Oda the legion of followers of Christ became augmented, many prisoners returned to their country, the shackled had their chains taken off, and the gates of prisons were opened for the trespassers."

Although Thietmar made no mention of warfare that possibly took place on this occasion, the information on the return of the accord, acting for the good of the country and release of prisoners indicate that a conflict actually did occur.

Archeology
Archaeological discoveries appear to support the thesis of Otto II's invasion. In the last quarter of the 10th century there had been a radical expansion of the fortifications at Gniezno and Ostrów Lednicki, which may be associated with the Polish-German war, or the expectation of such. The duration of the expedition suggests that it may have reached as far east as the vicinity of Poznań.