The Sunday of Orthodoxy is the first Sunday of Great Lent. The dominant theme of this Sunday since 843 has been that of the victory of the icons. In that year the iconoclastic controversy, which had raged on and off since 726, was finally laid to rest, and icons and their veneration were restored on the first Sunday in Lent.
Ever since, this Sunday has been commemorated as the "Triumph of Orthodoxy."