An angel of the LORD appeared to the woman
“Though you are barren and have had no children,
yet you will conceive and bear a son.
Now, then, be careful to take no wine or strong drink
and to eat nothing unclean.
As for the son you will conceive and bear,
no razor shall touch his head,
for this boy is to be consecrated to God from the womb.
It is he who will begin the deliverance of Israel
-- Jgs 13:2-7, 24-25a
Angels have been present since creation and throughout the history of salvation, announcing this salvation from afar or near and serving the accomplishment of the divine plan: they closed the earthly paradise; protected Lot; saved Hagar and her child; stayed Abraham's hand; communicated the law by their ministry; led the People of God; announced births and callings; and assisted the prophets, just to cite a few examples. Finally, the angel Gabriel announced the birth of the Precursor and that of Jesus himself.
-- CCC 332