Abstract: The object of this research is the Byzantine legends telling the tale of enacting the celebration of Akathist during the 5th Saturday of the Great Lent in connection with the war events. The article examines the question of valid historical connection between the siege of Constantinople of 626 AD and the liturgy of the 5th Saturday of the Great Lent (Akathist Saturday). The research also touches upon the question of connection between the 678 and 717 AD sieges with the aforementioned sacred service, as well as determines the possible causes for association of liberation of the Byzantine capital and the liturgy of the Akathist Saturday. The author proposes a new solution to the problem of inconsistency between the notes of various historical tales regarding the Akathist Saturday and liturgical sources. Possible causes are established for association of the liturgy of the Akathist Saturday and the memory of the siege of 626 AD. The author sequentially analyzes all available legends regarding the enactment and liturgical remembrance of sacred service of the Akathist Saturday.