Which roman era lasted the longest: the roman monarchy, the roman republic, the western roman empire or the byzantine empire?

one of the main reasons was definitely slavery. back in 1861, republican abraham lincoln was elected and ended up being a major influence in the slavery business. slavery greatly affected the texas economy because back in 1845 during the annexation of texas, slaves became a big part of the texas population. many texans that were in favor of the secession influenced groups through party ties.

its c not d   tell me if that´s correct