The Emperor Constans II had been so annoyed (or uninterested) in the debate over the two that he published a decree that the issue should not even be discussed. His son, Constantine IV, decided that the issue needed resolution, but that the emperor was not qualified to make that decision (and suffer the wrath of the losing side), so he wrote to the pope in Rome to find a way to solve the problem. Pope Agatho took up the challenge with several synods in the west that came up with an answer, which was then taken to Constantinople for the Sixth Ecumenical Council (which was also known as the Third Council of Constantinople, as depicted above in a painting in a church in Bucharest).
The imperial palace hosted 37 bishops on 7 November 680, with the patriarchs of Antioch and Constantinople. Patriarchs of Alexandria and Jerusalem were represented by proxy. A few priests and bishops from Rome were present, to represent the conclusion of the West that Jesus had dual natures. Constantine was present for many of the sessions, participating in the discussions; he was present at the closing session on 16 September 681, at which 151 bishops were present.
A letter from Pope Agatho was read, stating that Jesus was both human and divine; this had been commonly accepted for centuries. The majority accepted this. There were champions for Monothelitism, however. One of them, Patriarch Macarius of Antioch, claimed that Monothelitism had been proposed by ecumenical councils in the past and by statements from popes, but he was challenged to present that evidence. A letter from Pope Honorius to an earlier patriarch of Constantinople, Sergius I, seemed to express support for Monothelitism. The papal legates had no problem declaring that Honorius was wrong and needed to be condemned in the light of the current stance on Monothelitism.
During the months of debate, one proponent of Monothelitism attempted to prove the rightness of it (and of his faith in it) by declaring that he could in fact bring the dead back to life, proving that God was on his side in the debate. A corpse was found, and the priest whispered prayers into its ears, but the result one would expect took place. The corpse remained dead.
Macarius was deposed by the council; he and four others who would not relent on their belief were sent to Rome for "further instruction." Tomorrow, I'll tell you about the man who took on the responsibility of bringing Macarius back "into the fold" so to speak.