Even as the storm of persecution created by Emperor Valerian raged against the Church, the papal throne was not vacant. Sixtus, a Greek, was elected to succeed Stephen. The emperor's decrees had ordered the Christians to take part in state religious ceremonies and forbade them to assemble in cemeteries. For nearly a year Sixtus managed to evade the authorities before he was gloriously martyred.
Valerian issued his second edict ordering the execution of Christian bishops, priests, and deacons. Sixtus had taken to holding services in the private cemetery of Praetextatus because it was not watched as closely by the authorities as was the cemetery of Calixtus. But in early August of 258, while Sixtus was seated on his episcopal chair and surrounded by the brethren, the soldiers broke in arresting Sixtus and four deacons who were in attendance. After a formal judgment, Sixtus was led back to the very place where he had been arrested, to face execution. His chief deacon Lawrence, upon hearing the news, hastened to his side, desiring to die with his bishop. Sixtus consoled his deacon by telling him that he would follow in three days with even greater glory. The soldiers then placed Sixtus in his chair and swiftly beheaded him. True to the great pope's words, Lawrence was arrested three days later and executed the same day.
~Excerpted from The Popes: A Papal History, J.V. Bartlett