The great ‘Lorica’ or “Breastplate Prayer” of St. Patrick, the patron of the Land that Once was Ireland:

Sancti Patricii Hymnus ad Temoriam.

Ad Temoriam hodie potentiam
praepollentem invoco Trinitatis,
Credo in Trinitatem
sub unitate numinis elementorum.

Apud Temoriam hodie
virtutem nativitatis Christi cum ea ejus baptismi,
Virtutem crucifixionis cum ea ejus sepulturae,
Virtutem resurrectionis cum ea ascensionis,
Virtutem adventus ad judicium aeternum.

Apud Temoriam hodie
virtutem amoris Seraphim
in obsequio angelorum,
In spe resurrectionis
ad adipiscendum praemium.
In orationibus nobilium Patrum,
In praedictionibus prophetarum,
In praedicationibus apostolorum,
In fide confessorum,
In castitate sanctarum virginum,
In actis justorum virorum.

Apud Temoriam hodie
potentiam coeli,
Lucem solis,
Candorem nivis,
Vim ignis,
Rapiditatem fulguris,
Velocitatem venti,
Profunditatem maris,
Stabilitatem terrae,
Duritiam petrarum.

Ad Temoriam hodie potentia Dei me dirigat,
Potestas Dei me conservet,
Sapientia Dei me edoceat,
Oculus Dei mihi provideat,
Auris Dei me exaudiat,
Verbum Dei me disertum faciat,
Manus Dei me protegat,
Via Dei mihi patefiat,
Scutum Dei me protegat,
Exercitus Dei me defendat,
Contra insidias daemonum,
Contra illecebras vitiorum,
Contra inclinationes animi,
Contra omnem hominem qui meditetur injuriam mihi,
Procul et prope,
Cum paucis et cum multis.

Posui circa me sane omnes potentias has
Contra omnem potentiam hostilem saevam
Excogitatam meo corpori et meae animae;
Contra incantamenta pseudo-vatum,
Contra nigras leges gentilitatis,
Contra pseudo-leges haereseos,
Contra dolum idololatriae,
Contra incantamenta mulierum,
Et fabrorum ferrariorum et druidum,
Contra omnem scientiam quae occaecat animum hominis.

Christus me protegat hodie
Contra venenum,
Contra combustionem,
Contra demersionem,
Contra vulnera,
Donec meritus essem multum praemii.

Christus mecum,
Christus ante me,
Christus me pone,
Christus in me,
Christus infra me,
Christus supra me,
Christus ad dextram meam,
Christus ad laevam meam,
Christus hine,
Christus illine,
Christus a tergo.

Christus in corde omnis hominis quem alloquar,
Christus in ore cujusvis qui me alloquatur,
Christus in omni oculo qui me videat,
Christus in omni aure quae me audiat.

Ad Temoriam hodie potentiam
praepollentem invoco Trinitatis.
Credo in Trinitatem sub
Unitate numinis elementorum.
Domini est salus,
Domini est salus,
Christi est salus,
Salus tua, Domine,
sit semper nobiscum.

Amen.

Translation (imperfect, but unfortunately I’m not good enough of a Latinist to correct it):

The Lorica, Breastplate, of St. Patrick (The Cry of the Deer)

I arise today
Through a mighty strength, the invocation of the Trinity,
Through belief in the Threeness,
Through confession of the Oneness of the Creator of creation.

I arise today
Through the strength of Christ’s birth with His baptism,
Through the strength of His crucifixion with His burial,
Through the strength of His resurrection with His ascension,
Through the strength of His descent for the judgment of doom.
I arise today
Through the strength of the love of cherubim,
In the obedience of angels,
In the service of archangels,
In the hope of resurrection to meet with reward,
In the prayers of patriarchs,
In the predictions of prophets,
In the preaching of apostles,
In the faith of confessors,
In the innocence of holy virgins,
In the deeds of righteous men.

I arise today,
through The strength of heaven,
The light of the sun,
The radiance of the moon,
The splendor of fire,
The speed of lightning,
The swiftness of wind,
The depth of the sea,
The stability of the earth,
The firmness of rock.

I arise today,
through God’s strength to pilot me,
God’s might to uphold me,
God’s wisdom to guide me,
God’s eye to look before me,
God’s ear to hear me,
God’s word to speak for me,
God’s hand to guard me,
God’s shield to protect me,
God’s host to save me
From snares of devils,
From temptation of vices,
From everyone who shall wish me ill, afar and near.

I summon today
All these powers between me and those evils,
Against every cruel and merciless power that may oppose my body and soul,
Against incantations of false prophets,
Against black laws of pagandom,
Against false laws of heretics,
Against craft of idolatry,
Against spells of witches and smiths and wizards,
Against every knowledge that corrupts man’s body and soul;

Christ to shield me today
Against poison, against burning,
Against drowning, against wounding,
So that there may come to me an abundance of reward.

Christ with me,
Christ before me,
Christ behind me,
Christ in me,
Christ beneath me,
Christ above me,
Christ on my right,
Christ on my left,
Christ when I lie down,
Christ when I sit down,
Christ when I arise,
Christ in the heart of every man who thinks of me,
Christ in the mouth of everyone who speaks of me,
Christ in every eye that sees me, Christ in every ear that hears me.

I arise today
Through a mighty strength, the invocation of the Trinity,
Through belief in the Threeness,
Through confession of the Oneness of the Creator of creation.
Salvation is from the Lord,
Salvation is from the Lord,
Salvation is from Christ,
Your Salvation, O Lord,
is with us always.
Amen.