He engaged Karel Sabina, his comrade from the 1848 barricades, as his librettist, and received Sabina's text in February 1862, a story of the 13th century invasion of Bohemia by Otto of Brandenburg.
Han engagerede Karel Sabina, en kammerat fra barrikaderne i 1848, som sin librettist og fik Sabinas tekst i februar 1862, en historie om en invasion af Bøhmen af Otto Brandenburg i det 13. århundrede.