On the side of Leszek and his youngest brother Konrad fought the nobility of Kraków and Sandomierz, and the Rurikid Prince Roman of Vladimir-in-Volhynia.

In the first phase of the battle, the Greater Poland armies – personally commanded by Mieszko III and his son Bolesław – faced the forces of wojewoda Mikołaj and Prince Roman.

The supporters of Leszek and Konrad decided not to pursue the retreating enemy and returned to Kraków, because the casualties were great and among the injured was Prince Roman.

[citation needed] The withdrawal of Mieszko III the Old during the Battle of Mozgawą allowed Leszek (or more accurately, his regents) to maintain power for the next three years.

On behalf of her eldest son, the Dowager Duchess and Regent formally resigned his control of Kraków in exchange for recognition of his rights over Lesser Poland and Masovia, and receipt of Kujavia (for according to historians, Mieszko III and his son Bolesław had taken over the government of Kujavia after the death of Leszek, Duke of Masovia).

Konrad received Masovia and Kuyavia, while Leszek retained only Sandomierz, probably with the hope of eventually reconquering the Seniorate Province and the adjacent land of Sieradz-Łęczyca.

His former ally Mikołaj Gryfita, fearing his loss of political influence, demanded the dismissal of Leszek's closest collaborator, Goworek.

The wojewoda of Sandomierz was ready to step down in order to obtain Kraków for his master, but Leszek, unwilling to discard him, strongly refused this request.

In any case, some time after the death of Mikołaj Gryfita (also in 1202), the Kraków nobility invited Leszek to reassume the government without any conditions.

Roman then invaded the domains of Leszek and Konrad for unknown reasons (although historians believe that this was due to the intrigues of Władysław III), venturing deep into their territory.

Leszek and his brother initially led a coalition of Rurikid princes who wanted to remove Roman's children from Vladimir-in-Volhynia and Galicia.

[citation needed] A further confirmation of an active policy in Kievan Rus' were the marriages of Leszek and Konrad with Rurikid princesses.

[citation needed] In 1210 Andrew II decided to replace the reigning prince of Vladimir-in-Volhynia with Roman's eldest son Daniel.

The expected Polish-Hungarian confrontation did not occur in the end, because Leszek was forced to have his army return after Mieszko Tanglefoot captured Kraków.

In the same year, wanting to break the difficult relations with Hungary, Leszek, under the pressure of the Kraków aristocracy gathered around the voivode Pakosław, decided to conclude a peace treaty at Spiš.

[citation needed] Unfortunately, this alliance with Hungary did not last, because before the end of the year Leszek decided to support the restoration of Daniel Romanovich in Galicia when it was clear that the local nobility did not accept the rule of Prince Coloman.

The ambiguous policy of the Duke of Kraków cost him in 1215 when the Hungarians, impatient with the lack of help in securing the rule of Coloman, broke the alliance.

This new political approach failed to bring Leszek any positive results, because it prompted an alliance between Daniel Romanovich and Mstislav against him.

[citation needed] These successive failures forced Leszek to reconsider his previous alliance with Andrew II of Hungary.

The papal bull was a complete surprise for Leszek and the local church hierarchy who supported him, especially since both parties for the first time in Poland agreed upon the choice of the new Bishop of Kraków after the death of Fulka, the chronicler Wincenty Kadłubek.

[citation needed] Henryk Kietlicz, Archbishop of Gniezno — who had returned from exile some time before — decided to call the Synod of Borzykowa [pl], at which he tried to find a solution to this delicate issue.

Leszek, wanting to regain the support of the Church and the other rulers, bestowed a Great Privilege on the clergy, which ensured the integrity of territorial possession of the bishops.

Mieszko Tanglefoot was not present in Borzykowa; with the help of the Lesser Poland family of Gryfici, he went with his army to Kraków, where the confusion among the citizens as to who was actually in charge enabled him to take the capital without a fight.

Already in 1212 Leszek and his brother Konrad had a meeting in Mąkolno with Mestwin I of Pomerelia for the purpose of arranging a Christian mission that began only four years later when a bishop was sent, but without results.

[8] Initially, an attempt was made to convert the Prussians by peaceful means through special trading centers in which the pagans would become acquainted with the Christians.

The defeat and slaughter contributed significantly to the already cowardly attitude of the command of the Guard, a member of the Gryfici family, who was punished with exile.

[citation needed] A meeting of Polish Dukes was organized in the district of Gąsawa on the border of Kujawy and Greater Poland.

[citation needed] Older historiography noted that Leszek married only once, to Grzymisława, daughter of Ingvar Yaroslavich, Prince of Lutsk in 1207.

Wacława) in the city of Radom, which was further provided for by his son Bolesław V the Chaste, and in 1440 was extended and partially rebuilt in the Gothic style.