August is the time in which the Byzantine Church celebrates two great feasts: The Transfiguration of Our Lord (August 6th) and the Dormition (Falling Asleep) of the Theotokos (August 15th).
The Feast of the Dormition of the Theotokos, the most ancient feast of the Mother of God, directs our gaze towards what we are all called to as Christians: communion with the Lord for all eternity.
This call to re-dedication developed into a two week lent that Byzantines now call the “Dormition Fast”. The traditional rule for the Dormition Fast is a strict abstinence from August 1 to 14, with the usual mitigations (wine and oil) for Saturday and Sunday and the Feast of the Transfiguration (August 6). It is, therefore, observed as the Great Fast. The Ruthenian Metropolia has identified this period as a penitential season (Canon 880, § 2). The observance of this fast is voluntary.
In the 15th Century, from the eve of July 31st to August 15th, the Wood of the Cross was brought out from the imperial treasury and laid upon the altar of the great Church of Hagia Sophia in Constantinople. It became tradition to carry the relic of the Cross through the city in procession and offer it to the people to venerate.