• Upon Pope Liberius's death September 24 A.D. 366, violent disorders broke out over the choice of a successor. A group who had remained consistently loyal to Liberius immediately elected his deacon Ursinus in the Julian basilica and had him consecrated Bishop, but the rival faction of Felix's adherence elected Damasus, who did not hesitate to consolidate his claim by hiring a gang of thugs, storming the Julian Basilica in carrying out a three-day massacre of the Ursinians.
On Sunday, October 1 his partisans seized the Lateran Basilica, and he was there consecrated. He then sought the help of the city prefect (the first occasion of a Pope in enlisting the civil power against his adversaries), and he promptly expelled Ursinus and his followers from Rome. Mob violence continued until October 26, when Damasus's men attacked the Liberian Basilica, where the Ursinians had sought refuge; the pagan historian Ammianus Marcellinus reports that they left 137 dead on the field. Damasus was now secure on his throne; but the bishops of Italy were shocked by the reports they received, and his moral authority was weakened for several years....
Damasus was indefatigable in promoting the Roman primacy, frequently referring to Rome as 'the apostolic see' and ruling that the test of a creed's orthodoxy was its endorsement by the Pope.... This [false claim to] succession gave him a unique [presumptuous claim to] judicial power to bind and loose, and the assurance of this infused all his rulings on church discipline. — Kelly, J. N. D. (1989). The Oxford Dictionary of Popes. USA: Oxford University Press. pp. 32, 34;