Bayan fiye da karni na mulkin kasashen waje, Poland ta sami 'yancin kai a karshen yakin duniya na daya a matsayin daya daga cikin sakamakon shawarwarin da aka yi a taron zaman lafiya na Paris na 1919. Yarjejeniyar Versailles da ta fito daga taron da aka kafa. al'ummar Poland mai cin gashin kanta tare da hanyar shiga teku, amma ta bar wasu iyakokinta don yanke shawara ta hanyar plebiscites.Sauran iyakoki an daidaita su ta hanyar yaki da yarjejeniyoyin da suka biyo baya.An gwabza yaƙe-yaƙe guda shida na kan iyaka a cikin 1918-1921, gami da rikicin iyakar Poland da Czechoslovakia kan Cieszyn Silesia a cikin Janairu 1919.Kamar yadda waɗannan rikice-rikicen kan iyaka suka kasance cikin damuwa, Yaƙin Poland-Soviet na 1919-1921 shine mafi mahimmancin jerin ayyukan soja na zamanin.Piłsudski ya yi nisa da zane-zane mai nisa na adawa da Rasha a Gabashin Turai, kuma a cikin 1919 sojojin Poland sun tura gabas zuwa Lithuania, Belarus da Ukraine ta hanyar cin gajiyar shagaltuwar Rasha da yakin basasa, amma ba da daɗewa ba suka fuskanci Soviet yamma. shekara ta 1918-1919.Yammacin Ukraine ya riga ya zama gidan wasan kwaikwayo na Yaƙin Poland-Ukrainian, wanda ya kawar da shelar Jamhuriyar Jama'ar Yammacin Yukren a cikin Yuli 1919. A cikin kaka na 1919, Piłsudski ya ƙi amincewa da roƙon gaggawa daga tsoffin ikon Entente don tallafawa motsin Anton Denikin's White a gaba. Moscow.Yaƙin Poland-Soviet ya fara daidai da harin Kiev na Poland a cikin Afrilu 1920. Tare da haɗin gwiwa da Hukumar Kula da Yukren ta Jamhuriyar Jama'ar Ukrain, sojojin Poland sun wuce Vilnius, Minsk da Kiev a watan Yuni.A wancan lokacin, wani gagarumin farmaki da Tarayyar Soviet ta kai ya kori Poles daga mafi yawan Ukraine.A bangaren arewa kuwa, sojojin Soviet sun isa wajen birnin Warsaw a farkon watan Agusta.Nasarar Soviet da saurin ƙarshen Poland ya zama kamar babu makawa.Koyaya, Poles sun sami nasara mai ban mamaki a Yaƙin Warsaw (1920).Bayan haka, ƙarin nasarorin sojan Poland ya biyo baya, kuma Soviets sun ja da baya.Sun bar yankunan da ke da yawan jama'a na Belarusians ko Ukrain zuwa mulkin Poland.Zaman lafiya na Riga ya kammala sabuwar iyakar gabas a cikin Maris 1921.Kama Piłsudski na Vilnius a cikin Oktoba 1920 ya kasance ƙusa a cikin akwatin gawa na tsohuwar dangantakar Lithuania-Poland da ta yi rauni sakamakon Yaƙin Poland-Lithuania na 1919-1920;Dukkan jihohin biyu za su ci gaba da yin gaba da juna har tsawon lokacin da ake tsaka da yakin.Amincin Riga ya zaunar da iyakar gabas ta hanyar adanawa Poland wani yanki mai mahimmanci na tsoffin yankuna na gabas na Commonwealth akan farashin raba filayen tsohon Grand Duchy na Lithuania (Lithuania da Belarus) da Ukraine.'Yan Ukrain sun ƙare ba tare da wata ƙasa ta kansu ba kuma sun ji cin amana da shirye-shiryen Riga;bacin ransu ya haifar da matsananciyar kishin kasa da kyamar Poland.Yankunan Kresy (ko kan iyaka) a gabas da suka ci nasara ta 1921 zasu zama tushen tsarin musanya da Soviets suka tsara kuma suka aiwatar a cikin 1943-1945, wanda a wancan lokacin ya rama jihar Poland da ta sake kunno kai ga kasashen gabas da suka rasa. Tarayyar Soviet tare da mamaye yankunan gabashin Jamus.Sakamakon nasarar yakin Poland-Soviet ya bai wa Poland fahimtar karfinta a matsayin karfin soja mai cin gashin kansa kuma ya karfafa gwiwar gwamnati da ta yi kokarin warware matsalolin kasa da kasa ta hanyar samar da mafita na bai-daya.Manufofin yanki da na kabilanci na lokacin tsaka-tsaki sun ba da gudummawa ga mummunan dangantaka da yawancin maƙwabtan Poland da rashin haɗin gwiwa tare da ƙarin cibiyoyin iko, musamman Faransa da Birtaniya.