Donus was another old man elected Pope. He, too did not last very long.
A Roman, the son of Mauricius, Donus was named cardinal on 2 February 673 by Pope Adeodatus II. He was about 63 at the time. On June 17, 676, the old pope died. Donus was elected, but, in keeping with tradition, he waited for the Emperor to accept the election before he was consecrated. The consecration took place November 2, 676. The Church was without an official leader for four months and seventeen days. Being as Constantinople was under siege from the Muslims at the time, it is impressive that it only took that long.
Donus immediately went about restoring several churches in Rome. He had the atrium of the old St. Peter’s basilica paved with while marble. He repaired the Church of St. Euphremia and the basilica of St. Paul Outside the Walls.
For his diocese, Donus expanded his clergy, adding twelve priests and five deacons. He also consecrated six bishops to be sent abroad.
When Pope Vitalian excommunicated Archbishop Maurus of Ravenna for declaring himself independent of Rome, a schism began. It lasted only a few years. In 671, Maurus died and Reparatus was raised to the archbishopric. The emperor gave him his pallium. And Reparatus began the long road back from schism to obedience to the Holy See. Finally Reparatus claimed allegiance to Donus.
As Donus improved buildings in Rome, he found a Syrian monastery, the Boetianum. Within its walls lived monks who followed the Nestorian heresy. This theory was that Jesus had two entirely distinct natures, one divine and one human. Thus, Mary was not the mother of God, only of a man named Jesus. And the crucifixion was useless in saving man from sin, if only a man died. Donus was not about to have whole monastery preaching this. So he dispersed the monks amongst the other monasteries in the area and gave the monastery away.
Relations with Constantinople were conciliatory, without Donus approving the still popular Monothelite heresy. The Patriarch of Constantinople, Theodore, sent a vague letter to the new pope discussing unity. But, not including the required profession of faith, Donus did not accept it.
The emperor was fighting on two fronts. The Slavs had spent two years trying to take Thessalonica, finally failing in July of 678. The Muslims had a four year siege of Constantinople, finally giving up in the early fall. When the emperor was sure that he had the Muslims in hand and the capital city free of its siege, he turned his attentions to theology. In August of 678, Emperor Constantine IV wrote a letter to Donus suggesting a conference to discuss the differences of opinion regarding this heresy. He addressed the letter to “the most holy and blessed archbishop of our ancient Rome and the universal Pope”. Unfortunately, it was sent too late. The pope had died on April 11. It was Pope Agatho’s responsibility from here.
Donus was buried in Old St. Peter’s Basilica. He had ruled one year, five months and ten days.