Hedwig and Henry had several daughters, though only one surviving son, Henry II the Pious, who succeeded his father as Duke of Silesia and Polish High Duke. The widow, however, had to witness the killing of her son, vainly awaiting the support of Emperor Frederick II, during the Mongol invasion of Poland at the Battle of Legnica ("Wahlstatt") in 1241. The hopes for a re-united Poland were lost, and even Silesia fragmented into numerous Piast duchies under Henry II's sons. Hedwig and her daughter-in-law, Henry II's widow Anna of Bohemia, established a Benedictine abbey at the site of the battle in Legnickie Pole, settled with monks coming from Opatovice in Bohemia.