In the early years of his rule, Leszek's policy focused mainly in Kievan Rus'. In 1199 he helped Prince Roman of Vladimir-in-Volhynia with troops to reconquer the Principality of Halych, probably in gratitude for Roman's assistance against Mieszko III at Mozgawa in 1195. This alliance ended unexpectedly in 1205, however, when Roman decided to support Władysław III Spindleshanks' effort to recover the Seniorate Province (which supports the theory that Władysław III was expelled in 1202). 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. Both forces clashed in the Battle of Zawichost (14 October 1205), where Roman was defeated and killed.