See this online text:

In commemoration of the birth of St. Jadwiga, Queen of Poland (possibly 18 February 1374), and in remembrance of the Battle of Wesenberg, fought by Livonian Knights from the Terra Mariana (18 February 1268). For other legally free ebooks, you may access the List of Free eBooks (Arranged by Title) and the List of Free eBooks (Grouped by Subject).