"The Epistles & Hymn of Saint Patrick" by
Thomas Olden, Dublin 1876
Used
as a Lorica ( A “lorica” was a mystical garment
that was supposed to protect the wearer from danger and illness, and
guarantee entry into heaven.
) for protection by St. Patrick from the pagan Druids that lay in
ambush to intercept and kill him and his companions on their way to
the king's court. They did not see Patrick pass, only a doe followed
by her twenty fawns. Hence the name, "Deer's Cry".