The Pope Sixtus II reference article from the English Wikipedia on 24-Apr-2004
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Pope Sixtus II

Sixtus II, pope (257-258), followed Stephen I as bishop of Rome in 257, and suffered martyrdom under Valerian in the following year. He restored the relations with the African and Eastern churches which had been broken off by his predecessor on the question of heretical baptism.

Preceded by:
Pope Stephen I
List of popes Succeeded by:
Pope Dionysius