In 1157, the German Emperor Frederick Barbarossa launched a military campaign against Poland, defending the rights of Władysław, the eldest son of Bolesław III Wrymouth, who had been exiled by his brothers.

[3] As Barbarossa's forces advanced into Poland, the Piast rulers employed delaying tactics, obstructing paths with obstacles and cutting through forests to impede the enemy's progress.

[5] Barbarossa's detailed account of the invasion in his letter to Wibald, the abbot of Würzburg, highlighted the natural and artificial defenses encountered by the German army.

Notably, the absence of their preferred beverage, beer, led to discomfort among the German troops, resulting in a dysentery outbreak that claimed more lives than battles with the Polish forces.

[8] Despite the fortress's advantageous position on an island surrounded by rivers, the Polish garrison, recognizing the enemy's superiority, opted to abandon Głogów after setting it ablaze.

[9] The treaty stipulated that a part of the disputed Polish lands, claimed by Władysław II, who had been exiled by his younger brothers, be placed under imperial fief.

The pledge of peace in Krzyszkowo obligations was to send selected hostages from wealthy Polish families to the German Kingdom, as well as Casimir II the Just, the youngest brother of Bolesław and Mieszko III the Old.

[9] However, Boleslaw the Curly retained some autonomy and control over the Silesian province, including Głogów, under the recognition of Barbarossa, and he did not fulfill most of the provisions made during the peace in Krzyszkowo.