The First Synod of Tyre or the Council of Tyre (335 AD) was a gathering of bishops called together by Emperor Constantine I for the primary purpose of evaluating charges brought against Athanasius, the Patriarch of Alexandria.
Athanasius was involved in the early Christian christological and trinitarian debates, and supported the position of the Council of Nicaea in opposition to that of Arius and his followers.
In 328, Athanasius was elected as bishop or patriarch of Alexandria. Alexandria happened to be the city in which Arius was a priest. The situation was further complicated, as Athanasius had not yet reached the age of 30 - the minimum age for bishops in the church.
After Athanasius succeeded to the see of Alexandria, they had accused him of, among other things: immoral conduct, illegally taxing the Egyptian people, supporting rebels to the Imperial throne, and even murdering a bishop and keeping his severed hand for use in magical rites. More to the point, Constantine had decided that he wanted Athanasius to re-admit Arius to the church—which he would not do. In 334 Athanasius was summoned before a synod in Caesarea, which he did not attend.
The emperor Constantine had ordered a Synod of bishops to be present at the consecration of the church which he had erected at Jerusalem (the precursor to the Holy Sepulchre). He directed that, as a secondary matter, they should on their way first assemble at Tyre, to examine charges that had been brought against Athanasius. The Emperor also sent a letter to Athanasius, making clear that if he did not attend voluntarily, he would be brought to the Synod forcibly.