In 1076, Boleslaus II briefly re-instituted the office of king, but was banished in 1079 for murdering his opponent Bishop Stanislaus, who was then proclaimed a martyr and patron saint. In 1109, Boleslaus III Wrymouth defeated the King of Germany Henry V at the Battle of Hundsfeld, thus stopping the German incursion into Poland. The clash was documented by Gallus Anonymus in ''Gesta principum Polonorum'', the oldest Polish chronicle. In 1138, Poland fragmented into several smaller principalities when Boleslaus divided his lands among his sons. These comprised the Duchies of Lesser Poland, Greater Poland, Silesia, Masovia and Sandomierz, with Pomerania ruled by vassals. The division allowed each province to develop its own cultural identity and wealth, but made the country more vulnerable militarily.  In 1226, Konrad I of Masovia, one of the regional dukes, invited the Teutonic Knights to aid in combating the Baltic Prussian pagans; a decision that led to centuries of warfare with the Knights.