‘Augustine became a persecutor of a Christian sect called the Donatists. In the pre Constantine days of history the Romans persecuted the Christians of North Africa, who were divided into two groups; the Donatists and the Catholics.
The Donatists considered the Catholics traitors because they handed over the Scriptures to the Romans for burning. The Donatists were imprisoned by the Romans for their refusal to hand over the Scriptures. Even then the antagonism between the two Christian groups was so intense that the Catholics stood guard outside the prison. Any Donatist who dared to attempt to bring food to the imprisoned Donatists, who were well represented by their wives and children, were whipped and beaten, effectively preventing the delivery of food. Many Donatists died in prison from starvation.
Augustine in the last two decades of his life continued this persecution. By his own words, Augustine admits to stripping the Donatists of their property, an effective death sentence, not giving them the means of supporting their lives and imprisoning them. The Donatists claim Augustine did many deeds worse than even this.
The only crime of the Donatists were their desire to have their priests officiate the sacraments. The Catholics insisted the sacraments were only effective if delivered by their priests and outlawed all Donatist priests.
Peter Brown, a well known biographer, of Augustine will explain the Donatists and quote from one of Augustine’s works:
The Donatist bishops expounded the same Bible as himself, they professed the same creed, they celebrated an identical liturgy; yet they refused to see obvious truth about the Catholic Church – “They go down with eyes into Hell.”(C.Ep. Fund. 4)‘ 
source: Craig Fisher, “John Piper, the Profane” (craigcfisher).
 Peter Brown, Augustine of Hippo, A Biography (1967), p. 212.