Casimir III na Poland ya aririci Louis ya sa baki a yaƙin da ya yi da ’yan Lithuania da suka mamaye Brest, Volodymyr-Volynskyi, da wasu muhimman garuruwa a Halych da Lodomeria a shekarun baya.Sarakunan biyu sun amince cewa Halych da Lodomeria za su shiga cikin Masarautar Hungary bayan mutuwar Casimir.Louis ya ja-goranci sojojinsa zuwa Cracow a watan Yuni 1351. Domin Casimir ya yi rashin lafiya, Louis ya zama kwamandan sojojin Poland da na Hungaria tilo.Ya mamaye ƙasashen yariman Lithuania, Kęstutis, a watan Yuli.Kęstutis da alama ya karɓi suzerainty Louis a ranar 15 ga Agusta kuma ya yarda a yi masa baftisma, tare da 'yan uwansa, a Buda.Duk da haka, Kęstutis bai yi wani abu ba don cika alkawuransa bayan da aka janye sojojin Poland da na Hungary.A yunƙurin kama Kęstutis, Louis ya dawo, amma bai iya kayar da Lithuania ba, wanda har ma ya kashe ɗaya daga cikin abokansa, Boleslaus III na Płock, a yaƙi.Louis ya koma Buda kafin 13 ga SatumbaCasimir III ya kewaye Belz kuma Louis ya haɗu da kawunsa a cikin Maris 1352. A lokacin da aka kewaye shi, wanda ya ƙare ba tare da mika wuya na sansanin ba, Louis ya ji rauni sosai a kansa.Algirdas, Grand Duke na Lithuania, ya yi hayar ƴan hayar Tatar da suka shiga Podolia, Louis ya koma Hungary saboda yana tsoron mamayewar Tatar na Transylvania.Paparoma Clement ya yi shelar yaki da 'yan kasar Lithuania da Tatar a watan Mayu, inda ya ba Louis izinin karbar zakka daga kudaden shiga na Coci a cikin shekaru hudu masu zuwa.