St Anicetus was Pope between 155 and 166 although dates vary as much as five or six years either way. He was a Syrian from Emesa, as with other early Popes little else is know about him. Anicetus' saint day was on 17 April but is now suppressed following the 1969 revision of the Missal.
The main point of interest surrounding Anicetus' pontificate is the visit of St Polycarp Bishop of Smyrna. Polycarp was one of the last remaining disciples of St John and a leading figure in the Eastern church. As he had been taught by the Apostle Polycarp celebrated Easter on the 14th day of Nisan, regardless of which day of the week it fell on. The Roman tradition was to celebrate Easter on the Sunday which fell nearest to the date, as this was the actual day of the resurrection. Polycarp visited Rome with the intention of converting the Pope to the view of the Eastern church. Both men refused to budge but the discussion remained amicable at all times and Anicetus showed the great respect he had for the venerably Polycarp by allowing him to celebrate Easter on his chosen day whilst in Rome. Nothing was resolved and Anicetus agreed to allow the Eastern church to continue to celebrate on the 14th day of Nisan.
The gnostic heretics Marcon of Pontus, Marcellinus, Valentinus and Cerdon were still all active in Rome during Anicetus' time as Pope. Little is know about what action Anicetus took to combat the spread of heresy but the heresy was still present during the reign of Soter, Anicetus' successor. One decree is attributed to Anicetus by the Liber Pontificalis, it states that priests may not wear long hair, possibly because this was the custom of the gnostics.
The Catholic Encyclopaedia also remarks on the visit of Hegesippus to Rome during Anicetus' pontificate. Hegesippus was a key early church historian and wrote some of the only surviving accounts of Christianity at that time. J P Kirsch points out,
"His visit is recorded by most ecclesiastical authors as noteworthy, inasmuch as it calls attention to the fact that many illustrious men repaired to Rome at that period, thus emphasizing very early the supreme dignity and authority of the Roman Pontiffs."1
It was traditionally thought that he was martyred but modern sources deem this unlikely and attribute his title of martyr to the suffering he endured defending the faith against the gnostic heretics. However the normally balanced and reliable Catholic Encyclopaedia simply states, "Anicetus suffered martyrdom".1 While this may just be a slip on their part the authors normally make a point of discussing any debate or reasonable doubt over events. He was buried on the Vatican, possible in the Calixtine cemetery.
Pius I - Pope - Soter
1 - Catholic Encyclopaedia (http://www.newadvent.org/cathen/01514a.htm)