 Rambai muchinyora ndima ino - Mwanakomana mukuru waFerdinand I, Boris akatora chigaro mushure mekunge baba vake vasiya chigaro mushure mekukundwa kweBulgaria muHondo Yenyika I. Pasi peChibvumirano cheNeuilly cha1919, Bulgaria yakamanikidzwa, pakati pezvimwe zvinhu, kubvisa nzvimbo dzakasiyana siyana, kubhadhara muripo wehondo unoremadza, uye kuderedza zvakanyanya kukura kwemauto ayo. Mugore iroro, Aleksandar Stamboliyski womubatanidzwa wevagari venyika yeBulgaria Agrarian National Union akava mutungamiriri wehurumende. Pashure pokunge Stamboliyski adzingwa mukubvuta hurumendemuna 1923, Boris akabvuma hurumende itsva yaAleksandar Tsankov, uyo akadzvinyirira zvakasimba bato reCommunist reBulgaria uye akatungamirira rudzi rwacho kuburikidza nehondo pfupi yemuganhu neGreece. Tsankov akabviswa musimba muna 1926, uye nhevedzano yemakurukota makuru yakatevera kusvikira muna 1934, apo sangano reZveno rakaronga coup uye rakarambidza mapato ose ezvematongerwe enyika. Boris akapikisa hurumende yeZveno uye akavhiringidza muna 1935, pakupedzisira achigadza Georgi Kyoseivanov semutungamiriri wehurumende. Kwenguva yose yakasara youtongi hwake, Boris aizotonga sade facto mambo wechokwadi, uye vatungamiriri vake vehurumende vaizviisa pasi pake. 