felix festum Seraphicæ Virginis!

[Geremia]

Bl. Raymond of Capua, Legenda maior, III.1.334.937C-D:

Summus autem Pontifex [Gregorius XI] ea visa gavisus est, voluitque coram Cardinalibus, qui tunc aderant, quod verbum faceret exhortationis, potissime propter schisma, quod tunc incipiebat.	The Supreme Pontiff [Gregory XI] was clearly delighted to see her again and asked her to say a few words of encouragement to the Cardinals, especially with regard to the Schism, which had then just begun.
Quod et perfecte fecit, animando unumquemque eorum ad fortem constantiam verbis et sententiis plurimis, ac ostendendo divinam providentiam semper adesse cuilibet, sed potissime cum sancta Ecclesia patitur: et concludendo, quod propter inchoatum schisma in nullo trepidare deberent, sed agere quæ Dei sunt, et nullum timere.	[She] urged them with many arguments, which she expressed most felicitously, to be strong in constancy. She showed that divine providence is always with us, above all when the Church has to suffer, and ended by telling them not to be afraid of the schism that had just begun and to do the things of God and to fear no one.
[dixit Pontifex:] hæc muliercula nos confundit. Mulierculam autem voco, non in contemptum ejus sed in expressionem sexus feminei, naturaliter fragilis, et ad nostram instructionem.	[The Pope said:] A mere woman puts us to shame. I call her a 'mere woman', not out of disrespect, but with reference to her sex, which in itself is weak, and also for our own instruction.

[Geremia]

She's the great patroness of traditional Catholics!
She and her spiritual director, Bl. Raymond of Capua (Dominican master general), founded the Dominican Observant Reform Movement, which St. Vincent, fra' Girolamo Savonarola, et al. continued.
Her canonization was pivotal for ending the Great Western Papal "Schism".
Oret pro nobis!

[Geremia]

In preparation for her feast:

LITANIES DE SAINTE CATHERINE DE SIENNE Seigneur, avez pitié de nous. Jésus-Christ, ayez pitié de nous. Seigneur, ayez pitié de nous. Jésus-Christ, écoutez-nous. Jésus-Christ, exaucez-nous. Père céleste, qui êtes Dieu, ayez pitié de nous. Fils Rédempteur du monde, qui êtes Dieu, ayez pitié de nous. Esprit-Saint, qui êtes Dieu, ayez pitié de nous. Trinité sainte, qui êtes un seul Dieu, ayez pitié de nous. sainte Marie, priez pour nous. Sainte Catherine de Sienne, Chère fille de Dieu, Enfant privilégiée de Marie, Digne fille de saint Dominique, Fleur d'innocence, Fruit précoce des vertus, Image de simplicité, Parfait modèle d'humilité, Trésor de pureté, Ange de douceur, Défense de la foi, Bouclier d'espérance, Incendie d'amour, Vierge admirable, Épouse du Christ, O vous qui êtes l'épouse et l'amour du Seigneur Jésus, O vous qui avez été privée de votre cœur, O vous qui avez reçu le cœur de Jésus, O vierge, émule des plus saints pénitents, O vous qu1 avez senti un très vif amour pour la croix de Jésus, Vous qui avez toujours marché en la présence de Dieu en suivant la voie de la perfection, Vous dont l'âme fut entièrement détachée des choses terrestres et des sens, Vous qui avez été fréquemment ravie en Dieu, Vous qui avez toujours goûté la manne de l'oraison, Vierge illustre par le don du plus parfait recueillement, Vous qui avez été inviolablement liée à Dieu par une union très étroite, Vous qui avez été transformée dans le Christ, Vierge enrichie du don de prophétie, Chasseresse mystique des âmes que vous vouliez gagner à Dieu, Médiatrice puissante des âmes endurcies dans le mal, Auxiliatrice des pécheurs, Soutien des âmes fidèles, Colombe de grâce, Ange pacificateur des peuples, Colonne brillante de l'Église, Conseil des Pontifes, Terreur de l'hérésie, Gloire de l'Église, Gloire du Tiers-Ordre de Saint Dominique, Modèle de la parfaite obéissance, Modèle d'invincible patience, O vierge qui languissiez pour le ciel, O vierge riche de grâce et de vertus, O vierge couronnée de la persévérance, O vierge jouissant dans le ciel de l'éternel embrassement de votre époux. Agneau de Dieu, qui effacez les péchés du monde, pardonnez-nous, Seigneur. Agneau de Dieu, qui effacez les péchés du monde, exaucez-nous, Seigneur. Agneau de Dieu, qui effacez les péchés du monde, ayez pitié de nous, Seigneur. ℣. Seigneur, exaucez ma prière ℟. Et que mon cri parvienne jusqu'à vous. Prions. O Dieu, qui avez accordé à la bienheureuse Catherine, ornée du privilège spécial de la virginité et de la patience, de vaincre les efforts des esprits malfaisants et de demeurer inébranlable dans l'amour de votre nom, accordez, nous vous en supplions, qu'à son exemple, foulant aux pieds les méchancetés du monde et surmontant les attaques de tous les ennemis, nous arrivions en sécurité à votre gloire. Par Jésus-Christ Notre-Seigneur. Ainsi-soit-il.

LITANY OF SAINT CATHERINE OF SIENA Lord, have mercy on us. Jesus Christ, have mercy on us. Lord, have mercy on us. Jesus Christ, hear us. Jesus Christ, graciously hear us. Heavenly Father, who art God, have mercy on us. Redeemer Son of the world, who art God, have mercy on us. Holy Spirit, who art God, have mercy on us. Holy Trinity, who are one God, have mercy on us. Holy Mary, pray for us. Saint Catherine of Siena, Dear daughter of God, Privileged child of Mary, Worthy daughter of Saint Dominic, Flower of innocence, Early fruit of virtues, Image of simplicity, Perfect model of humility, Treasure of purity, Angel of gentleness, Defense of the faith, Shield of hope, Fire of love, Admirable virgin, Spouse of Christ, O you who are the bride and love of the Lord Jesus, O you who have been deprived of your heart, O you who received the heart of Jesus, O virgin, emulator of the holiest penitents, O you who have felt a deep love for the cross of Jesus, You who have always walked in God's presence, following the path of perfection, You whose soul was entirely detached from earthly things and the senses, You who have frequently been ravished in God, You who have always tasted the manna of prayer, Virgin illustrious for the gift of perfect recollection, You who were inviolably linked to God by a very close union, You who were transformed in Christ, Virgin enriched with the gift of prophecy, Mystical huntress of souls you wanted to win for God, Powerful mediatrix of souls hardened in evil, Helper of sinners, Support of faithful souls, Dove of grace, Angel peacemaker of peoples, Shining column of the Church, Council of Pontiffs, Terror of heresy, Glory of the Church, Glory of the Third Order of Saint Dominic, Model of perfect obedience, Model of invincible patience, O virgin who longed for heaven, O virgin rich in grace and virtue, O virgin crowned with perseverance, O virgin enjoying in heaven the eternal embrace of your spouse. Lamb of God, who takes away the sins of the world, forgive us, O Lord. Lamb of God, who takes away the sins of the world, hear us, O Lord. Lamb of God, who takes away the sins of the world, have mercy on us, Lord. ℣. Lord, answer my prayer. ℟. And let my cry come unto you. Let us pray. O God, who granted Blessed Catherine, adorned with the special privilege of virginity and patience, to overcome the efforts of evil spirits and remain steadfast in the love of your name, grant, we beseech you, that following her example, trampling underfoot the wickedness of the world and overcoming the attacks of all enemies, we may arrive safely at your glory. Through Jesus Christ Our Lord. Amen.

🎩-tip: Avrillé Dominicans's Litanies sainte Catherine de Sienne.pdf
🇫🇷→🇬🇧 transl. 🎩-tip: DeepL

[Geremia]

May the Seraphic Virgin obtain for us, by her heavenly intercession, a pope who returns to Eternal Rome! Happy feast! 🥳

One of her 1376 letters to then-Avignon-abiding Pope Gregory XI (from Saint Catherine of Siena as Seen in Her Letters; Italian original):

Come [back to Rome] in security: trust you in Christ sweet Jesus: for, doing what you ought, God will be above you, and there will be no one who shall be against you. Up, father, like a man! For I tell you that you have no need to fear. You ought to come; come, then. Come gently, without any fear.

(source)