Rubuta ci gaba don wannan sakin layi - A cikin sabuwar ƙarni, yayin da yaƙe-yaƙe suka zama marasa ƙarfi da ƙarancin lokaci, Brazil ta shiga cikin ƙaramin rikici tare da Bolivia don mallakar Acre, wanda Brazil ta samu a 1902. A shekara ta 1917 Brazil ta ayyana yaƙi da Tsakiyar Tsakiya, ta shiga bangaren kawance a Yaƙin Duniya na Farko kuma ta aika da karamin jirgi zuwa Bahar Rum da wasu sojoji don haɗuwa da sojojin Burtaniya da Faransa a yankin. Brazil ita ce kawai ƙasar Kudancin Amurka da ta shiga cikin Yaƙin Duniya na Farko. Daga baya a 1932 Colombia da Peru sun shiga cikin rikici na ɗan gajeren lokaci
don yankin a cikin Amazon. A cikin wannan shekarar Paraguay ta ba da sanarwar yaƙi da Bolivia don mallakar Chaco, a cikin rikicin da ya ƙare shekaru uku bayan haka tare da nasarar Paraguay. Tsakanin 1941 da 1942 Peru da Ecuador sun yi gwagwarmaya sosai don yankunan da suke da'awar duka waɗanda Peru ta haɗu da su, ta kwace iyakar Ecuador da Brazil.