Historical evidence of these efforts is in the prayer book sent to Mieszko by Frederick's wife, Matilda of Swabia, around 1027.

The gift was accompanied by a letter, wherein Matilda named him a distinguished king and a model for the spread of Christianity.

Also written was praise of the merits of Mieszko II in the building of new churches, as well his knowledge of Latin, very unusual in those times when Greek was more widely used.

In this book are found the earliest records of the Kingdom of Poland: neumes at the margins of the sequence Ad célèbres rex celica.

The devastation was so great that, according to Saxon sources, "where Mieszko II's troops put their feet grass never thence grew".

[1][better source needed] Despite the treaty which secured peace between Poland and Germany, the Emperor soon armed a retaliatory expedition against Mieszko II.

Conrad II's army arrived to Lusatia in the autumn of 1029 and began the siege of Bautzen, but the German troops did not receive the promised support of the Lutici tribe and the expedition failed.

Probably in exchange for Stephen I's support, Conrad II ceded to Hungary the territories between the Leitha and Fischa Rivers.

As a result, the Polish King lost portions of the lands taken by his father, who warred often against Emperor Henry II.

Mieszko II was not only imprisoned but also castrated, which was to be a punishment to Bolesław I the Brave, who blinded Duke Boleslaus III the Red (Oldřich's brother) thirty years before.