Two great historians of the
Church, Eusebius of Caesarea,
a bishop and historian of
the Council of Nicea, and Augustine,
bishop and theologian,
preserve for us the list of successors
of the bishop of Rome to
their own time. They attest to the
sense and realization the
Church had to the need for historic
succession to the Bishop of
Rome.
Eusebius
(260-339), The History of the
Church, Book 3, 324 AD
"After the martyrdom of
Paul and Peter, the
first man to be appointed
Bishop of Rome was
Linus. ... Linus, who is
mentioned in the
Second Epistle to Timothy as
being with
Paul in Rome, as stated above
was the first
after Peter to be appointed
Bishop of Rome.
Clement again, who became the
third Bishop
of Rome ... to Miltiades.
"