AMBARVALIA, an annual festival of the ancient Romans, occurring in May, usually on the 29th, the object of which was to secure the growing crops against harm of all kinds. The priests were the Arval Brothers (q.v.), who conducted the victims - ox, sheep and pig (suovetaurilia) - in procession with prayer to Ceres round the boundaries of the ager Romanus. As the extent of Roman land increased, this could no longer be done, and in the Acta of the Fratres, which date from Augustus, we do not find this procession mentioned (Henzen, Acta Fratrum Arvalium, 1874); but there is a good description of this or a similar rite in Virgil, Georg. i. 338 ff., and in Cato's work de Re Rustica (141) we have full details and the text of the prayers used by the Latin farmer in thus "lustrating" his own land. In this last case the god invoked is Mars. The Christian festival which seems to have taken the place of these ceremonies is the Rogation or Gang week of the Roman Church. The perambulation or beatinc of bounds is probably a survival of the same type of rite.
See W. W. Fowler, Roman Festivals (1899), p. 124 ff. (W. W. F.*)
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)