Started Midnight MassAccording to the Liber Pontificas, the tradition of Christmas Midnight Mass was started by Telesphorus, as well as the singing of Gloria in Excelsis Deo at it. Most scholars today however believe the tradition didn't start till centuries later.
EasterLike his predecessor Pope Sixtus I (115-125), Telesphorus also observed the Last Supper on the Roman Easter day instead of the traditional Jewish Passover day (14th of Nissan).
LentThe Liber Pontificalis also credits him with starting the first "Lent", by ordering a 7 week fast before Easter day. Public fasting was actually condemned by Jesus (Mat 6:16-18), and most scholars believe the practice was adopted from one of the pagan fastings of that time.
DeathOf the 14 bishops of Rome after Peter, historical verification for martyrs, exists only for Telesphorus; however, there are few details. Eusebius (Hist of the Church, IV, x) placed his death in the first year of Antoninus Pius' (138-161) reign. The apologist Irenaeus, wrote that his "death was made glorious by martyrdom". His remains are believed to be buried at the Vatican. His Feast Day is celebrated on Jan 5th, however in the Greek Church it is celebrated on Feb 22nd.
117-138: Roman Emperor, Hadrian
132-135: Simeon Bar-Kochba revolt, over 500'000 killed
135: Jerusalem captured and razed by Emperor Hadrian
Israel renamed Palestine (by Hadrian)