Rubuta ci gaba don wannan sakin layi - Gwamnan Buenos Aires Juan Manuel de Rosas ya yi amfani da karuwar rinjaye a kan sauran ƙasar a lokacin Gwamnatinsa na 1835-1852 kuma ya yi tsayayya da tayar da hankali na Unitarian da yawa, amma a ƙarshe ya ci nasara a 1852 da rundunar haɗin gwiwa da Gwamnan Entre Ríos Federalist Justo José de Urquiza ya tattara, wanda ya zargi Rosas da rashin bin ka'idodin Yarjejeniyar Tarayya don Tsarin Mulki na Kasa. A cikin 1853, an zartar da Tsarin Mulki na Tarayya (Kundin Tsarin Mulki na Argentina na yanzu, ta hanyar gyare-gyare) kuma an zabi Urquiza a matsayin Shugaban Tarayyar Argentina. Duk da haka, a bayan yakin Caseros na 1852
, lardin Buenos Aires ya rabu da Tarayyar. A cikin 1859, bayan Yaƙin Cepeda Jihar Buenos Aires ta sake shiga Tarayyar, kodayake an ba ta haƙƙin yin wasu gyare-gyare ga Kundin Tsarin Mulki. A ƙarshe, bayan Yaƙin Pavón na 1861, Buenos Aires ya karɓi ikon Tarayyar.