Henry, the incumbent patriarch of Aquileia, pledges his oath of fealty to Pope Gregory VII.
Sacramentum archiepiscopi Aquileiensis
Iuravit item eodem tempore archiepiscopus Aquileiensis Heinricus secundum haec verba:
“Ab hac hora et inantea fidelis ero et oboediens beato Petro et papę Gregorio suisque successoribus, qui per meliores cardinales intraverint.”
“Non ero in consilio neque in facto, ut vitam aut membra aut papatum perdant aut capti sint mala captione.”
“Ad synodum, ad quam me vocabunt vel per se vel per suos nuntios vel per suas litteras, veniam et canonice oboediam, aut, si non potero, legatos meos mittam.”
“Papatum Romanum et regalia sancti Petri adiutor ero ad tenendum et defendendum, salvo meo ordine.”
“Consilium vero, quod michi crediderint per se aut per nuntios suos sive per litteras, nulli pandam, me sciente, ad eorum damnum.”
“Legatum Romanum eundo et redeundo honorifice tractabo et in necessitatibus suis adiuvabo.”
“His quos nominatim excommunicaverint scienter non communicabo.”
“Romanam ecclesiam per secularem militiam fideliter adiuvabo, cum invitatus fuero.”
“Hęc omnia observabo, nisi quantum sua certa licentia remanserit.”
The oath of the archbishop of Aquileia
Likewise at this time [the synod of Rome, 11th of February, 1079], Henry, the archbishop of Aquileia, pledged an oath with the following words:
“From now henceforth I will be faithful to St. Peter and to Pope Gregory [VII] and to his successors who shall be elected by the better cardinals.”
“Neither in counsel nor in deed will I do anything to cause them to lose their life, or limb, or the papacy, or that they be taken prisoner through any treacherous trick.”
“To whatsoever synod they, either in person or by messenger or by letter, may call me, I will come and I will obey them according to the law; or if I shall not be able to come, I will send my representative.”
“I will aid and defend them in holding and defending the papacy and the regalia of St. Peter, saving the duties of my position.”
“If they, either in person or by messenger or by letter, shall entrust me with a secret, I will not knowingly reveal it to anyone to their harm.”
“I will treat with honor a papal legate, whether coming [from Rome] or going [back to Rome], and I will give him my aid whenever he needs it.”
“I will not wittingly associate with any whom the pope has excommunicated.”
Whenever I shall have been called on, I will aid the Roman church with my lay military forces.”
All these duties I will perform unless I shall have been excused from them.”
Trans. Oliver J. Thatcher and Edgar Holmes McNeal, A Source Book for Mediaeval History (New York–Chicago–Boston 1905), doc. 67 (slightly modified by the editor).
“Heinricus, Augustensis clericus qui a rege Heinrico investituram Aquileiensis ecclesie iam suscepit, electionem suam testimonio probabili canonicam esse ibidem testificatus est. Sed pro investitura contra canonicam et apostolicam sanctionem a laica persona sibi usurpata a papa reprobatus, diffinitionis eiusdem statutum se ignorasse et non audisse, synodo id ita iudicante, iureiurando palam comprobavit. Dehinc toto conventu pro eo in id ipsum apud papam intercedente, in primis, ut moris est, iustam et idoneam obedientiam ac subiectionem et suffragium Apostolice Sedi et sancti Petri vicario pape Gregorio per iusiurandum professus, ab eo anulum et virgam et cetera Aquileiensis Patriarchatus insignia canonice suscepit; sed non cum eo deinceps usquequaque fideliter egit.”
(“Henry, a clerk of Augsburg, who had already received investiture of the church of Aquileia from King Henry, testified there on the basis of credible evidence that his election was canonical. When, however, he was rejected by the pope because of the investiture that he had usurped for himself from a lay person contrary to the canonical and apostolic decree, he publicly confirmed on oath, according to the judgement of the synod, that he did not know and had never heard of the text of that decree. Then after the whole assembly had interceded for him with the pope in this matter, he firstly declared on oath his lawful and fitting obedience and subjection and support to the apostolic see and the vicar of St Peter, Pope Gregory, and received from him the ring and staff and the other insignia of the patriarchate of Aquileia according to canon law but he did not subsequently conduct himself faithfully towards him in all respects.”)
Berthold of Reichenau, Chronicle, ad annum 1079, ed. Ian S. Robinson, Die Chroniken Bertholds von Reichenau und Bernolds von Konstanz 1054–1100, Monumenta Germaniae historica, Scriptores rerum Germanicarum, nova series, 14 (Hannover 2003), p. 353; trans. Ian S. Robinson, Eleventh-century Germany: The Swabian Chronicles (Manchester 2008), p. 225.
“In eadem sinodo [Romae mense februario] Heinricus Aquileiensis patriarcha papae iuravit, nulli se deinceps communicaturum, quem sciret a papa excommunicatum.”
(“In the same synod [of Rome in the month of February] Henry, patriarch of Aquileia, swore to the pope that henceforward he would communicate with no one whom he knew to have been excommunicated by the pope.”)
Bernold of Constance, Chronicle, ad annum 1079, ed. Ian S. Robinson, Die Chroniken Bertholds von Reichenau und Bernolds von Konstanz 1054–1100, Monumenta Germaniae historica, Scriptores rerum Germanicarum, nova series, 14 (Hannover 2003), p. 422; trans. Ian S. Robinson, Eleventh-century Germany: The Swabian Chronicles (Manchester 2008), p. 264.
Patriarch Henry was elected to the chair of St. Hermaghoras by King Henry IV himself following the untimely death of Patriarch Sigehard in 1077. Since he served as the chaplain of the royal court, his election was a textbook example of the sort of "simony" the reform papacy led by Gregory VII was fighting against.
The situation was dire both for Patriarch Henry and for King Henry IV who had to face deal with two powerful enemies: Pope Gregory VII on the one side and the newly-elected anti-king Rudolph on the other. Patriarch Henry's pledge of loyalty must be conceptualized within this precarious situation.
In essence, the patriarch played a double game: he remained loyal to Henry but tried to appease the pope as well in order to stem the tide of enmity.
At first, the plan worked as Pope Gregory VII solemnly invested the non-canonically elected prelate as the new "archbishop" of Aquileia and even conceded him the privilege to don the pallium on the feast days of St. Ulrich and St. Afra, a token of their newly forged friendship - see the document edited here.
Afterward, however, the plan backfired as King Henry IV, outraged by this turn of events, dispossessed the Church of Aquileia of the two recently donated lands, the March of Carniola and the County of Istria which he gave to his faithful allies (Istria, and most probably Carniola as well, to Henry of House Eppenstein). See more on that here.
Patriarch Henry returned fully to support the pro-Henrician cause in the same year: he is mentioned as an intervener in Henry IV's charters already in October of 1079 (MGH DD H IV, docs. 317-318).
Moreover, he was one of the signees of the fateful Synod of Bressanone of 1080 which gathered the pro-imperial clergy and, led by King Henry IV, deposed Pope Gregory VII (edited in extenso in Card Erdmann (ed.), Die Briefe Heinrichs IV., Monumenta Germaniae historica, Deutsches Mittelalter: Kritische Studientexte (Leipzig 1937), pp. 69–73, available online).
Finally, he was excommunicated by Pope Gregory VII after, according to the contemporary chronicler Bernold of Constance, “he had more than once broken his oath to the lord pope.” (ad annum 1084, ed. Robinson, cited above).