Vratislav's son Sobeslaus I destroyed the Imperial army of King Lothar III in the Battle of Chlumec in 1126. This allowed a further strengthening of Bohemia, culminating during the reign of Vratislav's grandson, King Vladislaus II (1158). Vladislav II founded many monasteries and built the first stone bridge across the Vltava river, one of the earliest in Central and Northern Europe. Once again, internal struggles started the decline of the Přemyslids. Many leaders from the dynasty alternated on the Bohemian throne, leading to their eventual bankruptcy. Finally, on his ascension to the throne, Ottokar I began a series of changes that brought Bohemia out of crisis, and began a period of success that lasted for nearly 220 years.