Gaude Mater Polonia was one of the most significant medieval Polish hymns, written in Latin between the 13th and the 14th century to commemorate Saint Stanislaus, Bishop of Kraków. Polish knights sang and chanted the hymn after victory in battle, presumably to one of the Gregorian melodies associated with the Eucharistic psalm O Salutaris Hostia on which it is based. It's widely considered a historical, national anthem of the Kingdom of Poland and the Polish–Lithuanian Commonwealth.
A miniature depicting Saint Stanislaus of Szczepanów, painted by Stanisław Samostrzelnik (Stanislaus Claratumbensis).
Stanislaus of Szczepanów was a Polish Catholic prelate who served as Bishop of Kraków and was martyred by the Polish King Bolesław II the Bold. Stanislaus is venerated in the Catholic Church as Stanislaus the Martyr.
Saint Stanislaus. 16th-century illustration from the Catalogus Archiepiscoporum Gnesnensium.
Saint Stanislaus leads Piotr before the royal tribunal.
1- Saint Stanislaus being ordained as bishop. 2- Saint Stanislaus resurrects Peter. 3-King Bolesław murders Saint Stanislaus. 4-Stanislaus' body is cut into pieces. Image from the Hungarian Kings' Anjou Legendarium of the 14th century.
13th-century effigy of Saint Stanislaus
