Concerning the Harrowing of Hell:

A Warrior's Prayer from a fine book, written by a great man.

Lord of all power and might, Who art the Author and Giver of all good things, mercifully grant us grace valiantly to fight in Thy grace.  Give us the sure conviction that Thou art ever by our side.  Grant us in battle unflinching courage and an unconquerable spirit, so that no hurt nor obstacle may ever deter us from our duty.  And in victory, O Lord, grant us to be worthy of thine everlasting love and to continue Thy Faithful Soldiers and servants unto our life’s end,  and in this we beg for Jesus Christ, His sake. Amen.

[Taken from Thud Ridge, Colonel Jack Broughton, 1985, page 39, in which it is attributed (page 33) to “an old prayer of the Church of England, from the Middle Ages.”]