Anciently this feast was kept as a harvest festival in England - whence its name Lammas, from hlaf-mæsse (loaf-mass). But until the late pre-Conciliar reforms, or rather prunings, to-day was the feast of the Chains of St Peter (S. Petrus ad Vincula), the celebration of the hallowed fetters that held the Prince of the Apostles in his Roman prison (as earlier Herod had vainly enchained him), or rather, the celebration of his holding fast to Christ until death, death on an upside-down cross. This day is the anniversary of the consecration of the church of St Peter ad Vincula, called the Eudoxian Basilica after Princess Eudoxia who had it rebuilt in the fifth century.
But to-day is also the commemoration of the Holy Machabæan Martyrs, seven brothers and their mother put to death by Antiochus Epiphanes a century and a half before Christ: their great constancy under torture, their stedfast refusal to betray God and His Law, their belief in a future resurrection, all these make them great forerunners and models of Christian martyrs, and so the Fathers frequently preached. (Apparently their commemoration is held to-day because relics believed to be theirs were kept at the Church of St Peter in Chains.)
May the prayers of St Peter and these Martyrs unchain the bonds of sin that bind us: see my comments and the Collect and so forth that I quoted last year.