The following is taken from a 19th century Bragan cerimonial – Methodo da Liturgia Bracharense, by Antonio Thomaz dos Reis – describing how the Mandatum was to be carried out on Maundy Thursday in the archdiocese of Braga.
Of the Mandatum
A spot with carpets must be prepared within the church for the Mandatum; it must not be in front of the Blessed Sacrament, and should be decently adorned as much as possible. There shall be an altar at this spot, the Cross on it covered with a violet veil, and six white candles that shall be lit all throughout the action. On the Epistle side, a credence adorned with a cloth and upon it: magna towel with which the celebrant will gird himself; Evangeliary; missal, for the celebrant to say the verses and collect; jug with water; basin; pieces of bread; and towel for the celebrant to wash his hands at the end of the action. On the Gospel side, a long bench covered with rugs or green cloths for the thirteen washees. Another credence will be placed in a convenient and opportune spot, on which will be everything necessary for the washing: thirteen towels; needed jugs and basins; two or more trays, one to give to the celebrant the towel with which he will wash the foot, the other for alms; aromatic hot water and cold water for mixing; a large vessel for getting rid of the used water.
After dinner, when all is prepared, the celebrant puts on alb, stole and purple cope; the ministers violet dalmatics and maniples. The celebrant and ministers head towards the altar behind the thurifer, crucifer with unveiled cross and flanked by candle-bearers, Master of Ceremonies, etc. When they reach the altar, making due reverences to it and the choir, they go up to the benches and sit. The deacon receives the Evangeliary, puts it upon the altar, says the Munda cor meum &c, and with blessing, cross, candle-bearers, and incense de more until the incensing of the celebrant; he sings the Gospel of the Mandatum, which has neither Dominus vobiscum, nor Sequentia &c, but incensing the text begins with Ante diem &c.
The cross-bearer stands with the cross at that place where the Gospel will be sung, turned towards the Epistle side.
After the celebrant in incensed the ministers, having removed their maniples, remove his cope and gird him with a towel, and covered go to the place where the Mandatum will be done, preceded by the cross and necessary acolytes. When they arrive there they uncover themselves and reverence the washees, who will return the reverence standing and then be seated again. The ministers will then kneel next to the most worthy and the celebrant will wash, dry and kiss his right foot, which is held by the subdeacon to his left, while the deacon holds the water and towel to his right; the acolytes will minister the basins and give towels to the deacon. Afterwards the sacred ministers and the washee rise, and the celebrant gives him alms given by the deacon.
The Mandatum antifons as prescribed in the missal are begun as soon as the celebrant lowers himself to begin washing.
When the washing is finished the sacred ministers go to the credence where the celebrant washes his hands, who then goes to the benches to take off the towel with which he is girded and puts on the violet cope while the ministers put on their maniples. From there they go before the altar where the celebrant sings the Pater noster with verses and collect as in the missal. After this they retire.
If there is to be a sermon the preacher receives the blessing de more, and as he makes his way to the pulpit the sacred ministers sit for the sermon.