Prince of the Polish Piast dynasty, duke of Great Poland, duke of Krakôw, grand duke of Poland (1173-1177 and 1198-1202), and crusader.
Born between 1122 and 1125, Mieszko was the second surviving son of the Polish ruler Boleslaw III Krzywousty (Wrymouth), and Salome, daughter of Henry, count of Berg. Mieszko was a close ally of his elder brother, Prince Boleslaw IV Kçdzierzawy (the Curly) (d. 1173). He was married twice, to Elizabeth of Hungary and to Eudoksia of Kiev.
Mieszko and his brothers formed a coalition of the younger sons of Boleslaw III, who are known to scholars as the “Piast Juniors.” They opposed the rule of their step brother, Prince Wladyslaw II Wygnaniec (the Exile) (d. 1155), and with the support of the Polish magnates and prelates, they defeated him during the civil war (1142-1146).
Mieszko maintained an alliance with the rulers of the neighboring Saxon marches, for example, Albert the Bear, margrave of Brandenburg, and this alliance evidently influenced him to support the Wendish Crusade. In 1147 Mieszko commanded the Polish contingent of 20,000 troops (according to the Annales Magdeburgenses) against the pagan Slavs whose territories lay west of his duchy.
In 1187 Mieszko granted the Order of the Hospital patronage of the Church of St. John the Baptist in Poznan and possession of the hospital of St. Michael, established by Mieszko and Bishop Radwan of Poznan in 1170. The Poznan commandery of the Hospitallers was also established at this time.
Mieszko probably commissioned the door, known as the Porta Regia, which adorns the southern portal of the cathedral of Gniezno and is the most important work of Polish Romanesque art from the middle of the twelfth century. Its eighteen bas-relief panels illustrate events surrounding the life and death of St. Adalbert (Pol. Wojciech), the first patron saint of Poland, who was slain by pagan Prussians during a mission in 997. The commissioning of the Gniezno door coincided with Polish expansion north into pagan Prussian territories, and can be considered as an example of Piast propaganda portraying these events as holy wars.