Prayers for the Emperor at the Easter Vigil

In the First Epistle of St Peter, the Apostle tells us to honour the Emperor. Whilst it is usually translated as 'King' he uses the Greek for 'Emperor', βασιλέα. So there is a solid Scriptural basis for what follows.

Tonight in every Church of the Latin Rite, the glorious Easter Proclamation, the Exsultet will be sung. Here's a bit of forgotten history of the Liturgy of Easter Eve.

Until the year 1955, the Exsultet ended with a long prayer for the (Holy Roman) Emperor:

Respice etiam ad devotissimum imperatorem nostrum [Nomen] cujus tu, Deus, desiderii vota praenoscens, ineffabili pietatis et misericordiae tuae munere, tranquillum perpetuae pacis accommoda, et coelestem victoriam cum omni populo suo.

Look also upon our most devout Emperor [Name], the desires of whose longing you, O God, know beforehand, and by the inexpressible grace of your kindness and mercy grant him the tranquillity of lasting peace and heavenly victory with all his people.

Only the head of the Holy Roman Empire could be prayed for with this formula, and with the resignation in 1806 of the last emperor, Francis II of Austria, the prayer was in practice not used. The prayer now ended with the immediately preceding petition, for the members of the Church:

Precamur ergo te, Domine: ut nos famulos tuos, omnemque clerum, et devotissimum populum: una cum beatissimo Papa nostro N. et Antistite nostro N. quiete temporum assidua protectione regere, gubernare, et conservare digneris.

We beseech thee, therefore, O Lord, that we thy servants, and all the clergy, and the most devout people, together with our most blessed Pope N. and our Bishop N., may be deigned to govern, govern, and preserve us by the constant protection of the quiet times.

Also, until 1955, at the Good Friday intercessions, was included this prayer:

Let us pray also for our most Christian Emperor that the Lord God may reduce to his obedience all barbarous nations for our perpetual peace. O almighty and eternal God, in whose hands are all the power and right of kingdoms, graciously look down on the Roman Empire that those nations who confide in their own haughtiness and strength, may be reduced by the power of Thy right hand. Through the same Lord...

Further, there was a Votive Mass, Pro Imperatore (for the Emperor) included in the Missale Romanum until 1955. It used the following Collect:

O God, who didst prepare the Roman Empire for the preaching of the Gospel of the eternal King, extend to Thy servant, our Emperor, the armoury of heaven, so that the peace of the churches may remain undisturbed by the storms of war. Through Christ our Lord. Amen.

[This Collect was used also at the Coronation of an emperor, when the Emperor-elect was anointed by the Cardinal-bishop of Ostia, given the sword and orb by the Pope, ordained by him a Sub-deacon and then crowned Caesar semper Augustus, Romanorum Imperator with the sacred crown of Charlemagne, after which, as Deacon, he served the papal mass.]