Leszek II the Black
On 30 September 1288, Leszek II the Black, Duke of Sieradz and High Duke of Poland, died without issue. This event opened an opportunity for Henry IV to realize his ambitious plans to gain Kraków and the title of High Duke. With this purpose, he began to find suitable allies from 1287, when he reconciled with Przemysł II, returning him Wieluń. According to the Professor and Historian Oswald Balzer, shortly before began the preparations to the First Coalition of Piast Dukes formed by Leszek II the Black, Henry IV, Przemysł II and Henry III of Głogow, which had the intention to make the unification of Poland. Notwithstanding the veracity of this theory, after hearing the news of Leszek II's death, Henry IV was ready for action.