Editing Bolesław III Wrymouth (section)

====First Expedition to Bohemia and exile of Zbigniew====
In 1107 Bolesław III along with his ally King Coloman of Hungary invaded Bohemia in order to aid Svatopluk in gaining the Czech throne and to secure Polish interests to the south.<ref>R. Grodecki, S. Zachorowski, J. Dąbrowski: ''Dzieje Polski średniowiecznej'', vol. I, pp. 136–137.</ref> The expedition was a complete success: on 14 May 1107 Svatopluk was made Duke of Bohemia in [[Prague]].<ref>The date was given by Cosmas of Prague. At the news of the rebellion Bořivoj II (who was in the Congress of Merseburg) complained to Emperor Henry V and request his intervention. Z. S. Pietras: Bolesław Krzywousty. Cieszyn, 1978, pp. 90–91</ref>

In the winter of 1107–08, with the help of Kievan and Hungarian allies, Bolesław undertook a punitive expedition against his brother Zbigniew. One reason for this was that Zbigniew had not followed his orders and had refused to burn down one of the fortresses of [[Kurów]] near [[Puławy]].<ref>K. Maleczyński: ''Bolesław III Krzywousty'', p. 68.</ref> Another reason was that Zbigniew had not performed his duties as a vassal by failing to provide military aid to Bolesław for a campaign against the Pomeranians.  Bolesław's forces attacked Mazovia and quickly forced Zbigniew to surrender. Following this, Zbigniew was banished from the country and, with his followers, took refuge in Prague, where he gained the support of Svatopluk.<ref name="Barański, p. 201">M. K. Barański: ''Dynastia Piastów w Polsce'', p. 201.</ref> From then Bolesław was the sole lord of the Polish lands,<ref name="Grodecki, p. 137"/><ref>M. Spórna, P. Wierzbicki: ''Słownik władców Polski i pretendentów do tronu polskiego'', p. 63.</ref> though in fact his over-lordship began in 1107 when Zbigniew paid him homage as his feudal lord.<ref name="Szczur, p. 122"/>

In 1108 the balance of power in Europe changed. Svatopluk decided to pay homage to Emperor Henry V and in exchange received from him the formal investiture of Bohemia. At the same time King Coloman of Hungary was under attack from the combined forces of the Holy Roman Empire and Bohemia. Svatopluk, joined by Zbigniew and his followers, also attacked Poland. Bolesław avoided a direct confrontation because he was busy fighting Pomerania. The Polish-Hungarian coalition gave aid and shelter to Bořivoj II.<ref name="Barański, p. 201"/> Later that year, Bolesław and Coloman sent a new expedition to Bohemia, prompted by the invasion of Hungary by the German-Bohemian coalition (during which  [[Bratislava Castle|Pozsony Castle]] was put under siege)<ref name="Barański, p. 202">M. K. Barański: ''Dynastia Piastów w Polsce'', p. 202.</ref> and the fact that Svatopluk, who owed Bolesław his throne, didn't honor his promise to return Silesian cities seized from Poland ([[Racibórz]], Kamieniec, [[Koźle]] among others) by his predecessors.<ref name="Zachorowski, p. 141">R. Grodecki, S. Zachorowski, J. Dąbrowski: ''Dzieje Polski średniowiecznej'', vol. I , p. 141.</ref> Bolesław then decided to restore Bořivoj II to the Bohemian throne, but was unable to do so<ref name="Szczur, p. 122"/> owing to the need to divert his forces north to thwart a Pomeranian invasion.<ref name="Barański, p. 202"/>