As the secession movement grew he remained a staunch Unionist and was held for some time in a Confederate prison during the American Civil War.
He remained active in Republican Party politics during the Reconstruction Era and was a candidate for governor in 1868[2] with the backing of Louis Charles Roudanez and his African American newspaper The New Orleans Tribune.
As a delegate to the Louisiana state secessionist convention from Catahoula Parish, he argued strongly against leaving the American Union.
Taliaferro "denied the constitutional right [of a state] to leave the Union and painted a gloomy picture of economic chaos, blighted prosperity, staggering taxation and 'fatal prostration of Louisiana's interests under a southern Confederation,' and he could see no way ahead to prevent final anarchy and war.
"[5] In a speech to the convention, he said: My conscience is my guide; my judgment and patriotism approve, and though I am scorned and hissed, I am willing to abide the arbitrament of time and events as to the correctness of my course.
The act I denounce as one of mad folly, and of which, if my judgment errs not, every signer of that paper will come to be ashamed; and for one, it shall not herald my name to the future infamy which I predict will be its fate.