Mieszko I of Poland and half a century later, by Bishop Thietmar of Merseburg. By the time Mieszko I took over from his father, the Polans' tribal federation of Greater Poland had for some time been actively expanding. Continuing this process, perhaps in the first years of Mieszko's reign, if it had not been done already by his father, Mieszko I conquered Masovia. Likely also during that period or earlier, at least partially Gdańsk Pomerania was obtained. Mieszko's interests were then concentrated mainly on areas occupied by the eastern (near the Oder River) branches of the Polabian Slavs; some of them became soon subordinated
Mieszko I Tanglefoot Casimir II's eldest son, Leszek the White. Both sides clashed in the bloody Battle of Mozgawa (Mozgawą) near Jędrzejów (13 September 1195), where Mieszko III was seriously injured and his son Bolesław of Kuyavia died. The Silesian troops, led by Mieszko and Jarosław, arrived to the battlefield too late, soon after Mieszko III withdrew to Kalisz. Despite the forces of the Count palatine Goworek who also arrived to help Leszek's troops, the Silesians obtained a great victory; however, because Mieszko III wasn't present, this victory brought to them only benefits in terms of prestige (not counting the ransoms obtained by