How did Saint Augustine become a saint?

There are dozens of saints named Augustine. You need to be specific.

Saint Augistine was made a Saint shortly after his death in 604 AD by local acclaim. This was long before more modern processes of official canonization.

There are a number of saints with that name so you need to be more specific if you wish an answer.

St. Regina remained steadfast in her Christian faith even in the face of torture and death. When the proconsul Olybrius wanted to marry the humble shepherdess and demanded that she abandon her...

St. Monica was a devout Catholic mother who was married to an abusive and unfaithful pagan husband. Her son, Augustine, had a misspent youth and that followed him into his younger adult years. Monica...