Gregory was born as Hildebrand in Sovana, in what is now southern Tuscany, central Italy. He was said to be of humble origins. According to Johann Georg Estor his birth name was Hildebrand Bonizi and he was the son of a blacksmith. As a youth he was sent to Rome, where, according to some unconfirmed sources, his uncle was abbot of a monastery on the Aventine Hill, to study. Among his masters were the erudite Lawrence, archbishop of Amalfi and the future Pope Gregory VI. When the latter was deposed by Henry III and exiled to Germany, Hildebrand followed him to Cologne.

According to some chroniclers, Hildebrand moved to Cluny after Gregory's death; his declaration to have become a monichus in that convent must not be taken literally. He then accompanied Abbot Bruno of Toul in Rome; there, Bruno was elected Pope, choosing the name Leo IX, and named Hildebrand as deacon and papal administrator. Leo sent Hildebrand as his legate to Tours in France in the wake of the controversy raised by Berengar of Tours. At Leo's death, the new Pope Victor II confirmed him as legate, while Victor's successor Stephen IX sent him and Anselm of Lucca to Germany to obtain recognition from Empress Agnes de Poitou. Stephen died before being able to return to Rome, but Hildebrand was successful; he was then instrumental in overcoming the crisis caused by the Roman aristocracy's election of an antipope, Benedict X, whom, thanks also to Agnes' support, was replaced by the Bishop of Florence, Nicholas II. With the help of 300 Norman knights sent by Richard of Aversa, Hildebrand personally led the conquest of the castle of Galeria, where Benedict had taken refuge. Between 1058 and 1059, he was created archdeacon of the Roman church, becoming the most important figure in the Papal administration.

He was again the most powerful figure behind the election of Anselm of Lucca the Elder as Pope Alexander II in the October 1061. The new Bishop of Rome put forward the reformation programme devised by Hildebrand and his followers. In his years as papal advisor, Hildebrand had an important role in the reconciliation with the Norman kingdom of southern Italy, in the anti - German alliance with the Pataria movement in northern Italy and, above all, in the introduction of a law which gave the cardinals exclusive right concerning the election of a new Bishop of Rome.

On the death of Alexander II (April 21, 1073), as the obsequies were being performed in the Lateran Basilica, there arose a loud outcry from the clergy and people: "Let Hildebrand be pope!", "Blessed Peter has chosen Hildebrand the Archdeacon!" Later, on the same day, Hildebrand was conducted to the church of San Pietro in Vincoli, and there elected in legal form by the assembled cardinals, with the due consent of the Roman clergy and amid the repeated acclamations of the people. That this extraordinary outburst on the part of the clergy and people in favour of Hildebrand could have been the result of some preconcerted arrangements, as is sometimes alleged, does not appear likely. Hildebrand became Pope, taking the name of Gregory VII. The mode of his election was highly criticized by his opponents. Many of the charges brought may have been expressions of personal dislike, liable to suspicion from the very fact that they were not raised to attack his promotion until several years later; but it is clear from his own account of the circumstances of his election that it was conducted in a very irregular fashion, and that the forms prescribed by the law of 1059 were not observed; above all, the requirement of Pope Nicholas II that the German Emperor be consulted in the matter. However, what ultimately turned the tide in favour of validity of Gregory's election was the near universal acclaim of the populus Romanus. In this sense, his election hearkened back to the earliest centuries of the Church of Rome, regardless of later canonical legislation. Gregory's earliest pontifical letters clearly acknowledge this fact, and thus helped defuse any doubt about his election as immensely popular. On May 22 he received presbyteral ordination, and on June 30 was ordained to as a bishop.

In the decree of election those who had chosen him as Bishop of Rome proclaimed Gregory VII "a devout man, a man mighty in human and divine knowledge, a distinguished lover of equity and justice, a man firm in adversity and temperate in prosperity, a man, according to the saying of the Apostle, of good behaviour, blameless, modest, sober, chaste, given to hospitality, and one that ruleth well his own house; a man from his childhood generously brought up in the bosom of this Mother Church, and for the merit of his life already raised to the archidiaconal dignity". "We choose then", they said to the people, "our Archdeacon Hildebrand to be pope and successor to the Apostle, and to bear henceforward and forever the name of Gregory" (April 22, 1073).

His first attempts in foreign policy were towards a reconciliation with the Normans of Robert Guiscard; in the end the two parties did not meet. After a failed call for a crusade to the princes of northern Europe, and after obtaining the support of other Norman princes such as Landulf VI of Benevento and Richard I of Capua, Gregory was able to excommunicate Robert in 1074. In the same year Gregory summoned a council in the Lateran palace, which condemned simony and confirmed celibacy for the Church's clergy. These decrees were further stressed, under menace of excommunication, the next year (February 24 – 28). In particular, in this second council Gregory decreed that that only the Pope could appoint or depose bishops or move them from see to see, an act which was later to cause the Investiture Controversy.

The main focus of the ecclesiastico - political projects of Gregory VII is however to be found in his relationship with Germany. Since the death of Henry III the strength of the German monarchy had been seriously weakened, and his son Henry IV had to contend with great internal difficulties. This state of affairs was of material assistance to Gregory. His advantage was further accentuated by the fact that in 1073 Henry was only twenty - three and thus inexperienced.

In the two following years Henry was forced by the Saxon Rebellion to come to amicable terms with Gregory VII at any cost. Consequently in May 1074 he did penance at Nuremberg - in the presence of the papal legates - to atone for his continued friendship with the members of his council who had been banned by Gregory, took an oath of obedience, and promised his support in the work of reforming the Church. This attitude, however, which at first won him the confidence of the pope, was abandoned as soon as he defeated the Saxons by his victory at the First Battle of Langensalza on June 9, 1075 (also called the Battle of Homburg or Battle of Hohenburg). Henry then tried to reassert his rights as the sovereign of northern Italy without delay. He sent Count Eberhard to Lombardy to combat the Patarenes; nominated the cleric Tedaldo to the archbishopric of Milan, thus settling a prolonged and contentious question; and finally tried to establish relations with the Norman duke, Robert Guiscard.

Gregory VII replied with a rough letter, dated December 8, in which, among other charges, he accused the German king of breaching his word and with his continued support of the excommunicated councillors; while at the same time he sent a verbal message suggesting that the enormous crimes which would be laid to his account rendered him liable, not only to the ban of the Church, but to the deprivation of his crown. Gregory did this at a time when he himself was confronted by a reckless opponent in the person of Cencio I Frangipane, who on Christmas night surprised him in church and carried him off as a prisoner, though on the following day Gregory was released.

The reprimands of the Pope, couched as they were in such an unprecedented form, infuriated Henry and his court, and their answer was the hastily convened national council in Worms, Germany (synod of Worms), which met on January 24, 1076. In the higher ranks of the German clergy Gregory had many enemies, and a Roman cardinal, Hugo Candidus, once on intimate terms with him but now his opponent, had hurried to Germany for the occasion. All the accusations with regard to Gregory that Candidus could come up with were well received by the assembly, which committed itself to the resolution that Gregory had forfeited the papacy. In one document full of accusations, the bishops renounced their allegiance to Gregory. In another Henry pronounced him deposed, and the Romans were required to choose a new pope. The council sent two bishops to Italy, and they procured a similar act of deposition from the Lombard bishops in the synod of Piacenza. Roland of Parma informed the pope of these decisions, and he was fortunate enough to gain an opportunity for speech in the synod, which had just assembled in the Lateran Basilica, and he delivered his message there announcing the dethronement. For the moment the members were frightened, but soon such a storm of indignation was aroused that it was only due to the moderation of Gregory himself that the envoy was not murdered.

On the following day the Pope Gregory pronounced the sentence of excommunication against Henry IV with all due solemnity, divested him of his royal dignity and absolved his subjects from the oaths they had sworn to him. The act of excommunicating a king was incredibly bold, but not without precedent. Pope Zachary had brought significant challenges to rulers of his era a full 200 years earlier, in a move Thomas Hobbes famously called one of the greatest abuses of the Papacy in the history of the Church. This sentence purported to eject a ruler from the Church and to strip him of his crown. Whether it would produce this effect, or would be an idle threat, depended not so much on Gregory as on Henry's subjects, and, above all, on the German princes. Contemporary evidence suggests that the excommunication of Henry made a profound impression both in Germany and Italy. Thirty years before, Henry III had deposed three claimants to the papacy, and thereby rendered an acknowledged service to the Church. When Henry IV tried to copy this procedure he was less successful, as he lacked the support of the people. In Germany there was a rapid and general feeling in favour of Gregory, and the princes took the opportunity to carry out their anti - regal policy under the cloak of respect for the papal decision. When at Whitsun the king proposed to discuss the measures to be taken against Gregory in a council of his nobles, only a few made their appearance; the Saxons snatched at the golden opportunity for renewing their rebellion, and the anti - royalist party grew in strength from month to month.

Gregory VII was seen by Pope Paul VI as instrumental in affirming the tenet that Christ is present in the Blessed Sacrament. Gregory's demand that Berengarius perform a confession of this belief was quoted in Pope Paul VI's historic 1965 encyclical Mysterium Fidei:

I believe in my heart and openly profess that the bread and wine that are placed on the altar are, through the mystery of the sacred prayer and the words of the Redeemer, substantially changed into the true and proper and life giving flesh and blood of Jesus Christ our Lord, and that after the consecration they are the true body of Christ.

This profession of faith began a "Eucharistic Renaissance" in the churches of Europe as of the 12th century.

The situation now became extremely critical for Henry. As a result of the agitation, which was zealously fostered by the papal legate Bishop Altmann of Passau, the princes met in October at Trebur to elect a new German ruler; Henry, who was stationed at Oppenheim on the left bank of the Rhine, was only saved from the loss of his throne by the failure of the assembled princes to agree on the question of his successor. Their dissension, however, merely induced them to postpone the verdict. Henry, they declared, must make reparation to Gregory and pledge himself to obedience; and they decided that, if, on the anniversary of his excommunication, he still lay under the ban, the throne should be considered vacant. At the same time they decided to invite Gregory to Augsburg to decide the conflict. These arrangements showed Henry the course to be pursued. It was imperative, under any circumstances and at any price, to secure his absolution from Gregory before the period named, otherwise he could scarcely foil his opponents in their intention to pursue their attack against him and justify their measures by an appeal to his excommunication. At first he attempted to attain his ends by an embassy, but when Gregory rejected his overtures he took the celebrated step of going to Italy in person.

Gregory VII had already left Rome, and had intimated to the German princes that he would expect their escort for his journey on January 8 in Mantua. But this escort had not appeared when he received the news of Henry's arrival. Henry, who had travelled through Burgundy, had been greeted with enthusiasm by the Lombards, but resisted the temptation to employ force against Gregory. He chose the unexpected course of forcing Gregory to grant him absolution by doing penance before him at Canossa, where he had taken refuge. This event soon became legendary. The reconciliation was only effected after prolonged negotiations and definite pledges on the part of Henry, and it was with reluctance that Gregory at length gave way. This was because for, if Gregory gave absolution, the diet of princes in Augsburg, in which he might reasonably hope to act as arbitrator, would either become useless, or, if it met at all, would change completely in character. It was impossible, however, to deny the penitent re-entrance into the Church, and Gregory's religious obligations overrode his political interests.

The removal of the ban did not imply a genuine reconciliation, and no basis was gained for a settlement of the main question: that of investiture. A new conflict was inevitable from the very fact that Henry considered the sentence of deposition repealed along with that of excommunication; while Gregory on the other hand was intent on reserving his freedom of action and gave no hint on the subject at Canossa.

That the excommunication of Henry IV was simply a pretext for the opposition of the rebellious German nobles is transparent. Not only did they persist in their policy after his absolution, but they took the more decided step of setting up a rival ruler in the person of Duke Rudolf of Swabia (Forchheim, March 1077). At the election the papal legates present observed the appearance of neutrality, and Gregory himself sought to maintain this attitude during the following years. His task was made easier in that the two parties were of fairly equal strength, each trying to gain the upper hand by getting the pope on their side. But the result of his non - committal policy was that he largely lost the confidence of both parties. Finally he decided for Rudolf of Swabia after his victory at the Battle of Flarchheim (January 27, 1080). Under pressure from the Saxons, and misinformed as to the significance of this battle, Gregory abandoned his waiting policy and again pronounced the excommunication and deposition of King Henry (March 7, 1080).

But the papal censure now proved a very different thing from the one four years before. It was widely felt to be an injustice, and people began to ask whether an excommunication pronounced on frivolous grounds was entitled to respect. To make matters worse, Rudolf of Swabia died on October 16 of the same year. A new claimant, Hermann of Luxembourg, was put forward in August 1081, but his personality was not suitable for a leader of the Gregorian party in Germany, and the power of Henry IV was at its peak. The king, now more experienced, took up the struggle with great vigour. He refused to acknowledge the ban on the ground of its illegality. A council had been summoned at Brixen, and on June 16 it pronounced Gregory deposed and nominated the archbishop Guibert of Ravenna as his successor. In 1081 Henry opened the conflict against Gregory in Italy. The latter had now become less powerful, and thirteen cardinals deserted him.

The pope's chief military supporter, Matilda of Tuscany, blocked Henry's from the western passages over the Apennines, so he had to approach Rome from Ravenna. Rome surrendered to the German king in 1084, and Gregory thereupon retired into the exile of Sant' Angelo, and refused to entertain Henry's overtures, although the latter promised to hand over Guibert as a prisoner, if the sovereign pontiff would only consent to crown him emperor. Gregory, however, insisted as a necessary preliminary that Henry should appear before a council and do penance. The emperor, while pretending to submit to these terms, tried hard to prevent the meeting of the bishops. A small number however assembled, and, in accordance with their wishes, Gregory again excommunicated Henry. Henry upon receipt of this news again entered Rome on March 21 to see that Guibert of Ravenna be enthroned as Clement III (March 24, 1084). Henry was crowned emperor by his creature, but Robert Guiscard, with whom in the meantime Gregory had formed an alliance, was already marching on the city, and Henry fled towards Civita Castellana. The pope was liberated, but, the people becoming incensed by the excesses of his Norman allies, he was compelled to withdraw to Monte Cassino, and later to the castle of Salerno by the sea, where he died in the following year. Three days before his death he withdrew all the censures of excommunication that he had pronounced, except those against the two chief offenders — Henry and Guibert.

The relationship of Gregory to other European states was strongly influenced by his German policy; as Germany, by taking up most of his powers, often forced him to show to other rulers the very moderation which he withheld from the German king. The attitude of the Normans brought him a rude awakening. The great concessions made to them under Nicholas II were not only powerless to stem their advance into central Italy but failed to secure even the expected protection for the papacy. When Gregory was hard pressed by Henry IV, Robert Guiscard left him to his fate, and only intervened when he himself was threatened with German arms. Then, on the capture of Rome, he abandoned the city to his troops, and the popular indignation evoked by his act brought about Gregory's exile.

In the case of several countries, Gregory tried to establish a claim of sovereignty on the part of the Papacy, and to secure the recognition of its self - asserted rights of possession. On the ground of "immemorial usage", Corsica and Sardinia were assumed to belong to the Roman Church. Spain and Hungary were also claimed as her property, and an attempt was made to induce the king of Denmark to hold his realm as a fief from the pope. Philip I of France, by his practice of simony and the violence of his proceedings against the Church, provoked a threat of summary measures; and excommunication, deposition and the interdict appeared to be imminent in 1074. Gregory, however, refrained from translating his threats into actions, although the attitude of the king showed no change, for he wished to avoid a dispersion of his strength in the conflict soon to break out in Germany. In England, William the Conqueror also derived benefits from this state of affairs. He felt himself so safe that he interfered autocratically with the management of the church, forbade the bishops to visit Rome, made appointments to bishoprics and abbeys, and showed little anxiety when the pope lectured him on the different principles which he had as to the relationship of spiritual and temporal powers, or when he prohibited him from commerce or commanded him to acknowledge himself a vassal of the apostolic chair. Gregory had no power to compel the English king to an alteration in his ecclesiastical policy, so he chose to ignore what he could not approve, and even considered it advisable to assure him of his particular affection.

Gregory, in fact, established some sort of relations with every country in Christendom; though these relations did not invariably realize the ecclesiastico - political hopes connected with them. His correspondence extended to Poland, Kievan Rus' and Bohemia. He unsuccessfully tried to bring Armenia into closer contact with Rome. He was particularly concerned with the East. The schism between Rome and the Byzantine Empire was a severe blow to him, and he worked hard to restore the former amicable relationship. Gregory successfully tried to get in touch with the emperor Michael VII. When the news of the Arab attacks on the Christians in the East filtered through to Rome, and the political embarrassments of the Byzantine emperor increased, he conceived the project of a great military expedition and exhorted the faithful to participate in recovering the Church of the Holy Sepulchre. In his treatment of ecclesiastical policy and ecclesiastical reform, Gregory did not stand alone, but found powerful support: in England Archbishop Lanfranc of Canterbury stood closest to him; in France his champion was Bishop Hugo of Dié, who afterwards became Archbishop of Lyon.

His life work was based on his conviction that the Church was founded by God and entrusted with the task of embracing all mankind in a single society in which divine will is the only law; that, in her capacity as a divine institution, she is supreme over all human structures, especially the secular state; and that the pope, in his role as head of the Church, is the vice regent of God on earth, so that disobedience to him implies disobedience to God: or, in other words, a defection from Christianity. But any attempt to interpret this in terms of action would have bound the Church to annihilate not merely a single state, but all states. Thus Gregory, as a politician wanting to achieve some result, was driven in practice to adopt a different standpoint. He acknowledged the existence of the state as a dispensation of Providence, described the coexistence of church and state as a divine ordinance, and emphasized the necessity of union between the sacerdotium and the imperium. But at no period would he have dreamed of putting the two powers on an equal footing; the superiority of church to state was to him a fact which admitted of no discussion and which he had never doubted.

He wished to see all important matters of dispute referred to Rome; appeals were to be addressed to himself; the centralization of ecclesiastical government in Rome naturally involved a curtailment of the powers of bishops. Since these refused to submit voluntarily and tried to assert their traditional independence, his papacy is full of struggles against the higher ranks of the clergy.

This battle for the foundation of papal supremacy is connected with his championship of compulsory celibacy among the clergy and his attack on simony. Gregory VII did not introduce the celibacy of the priesthood into the Church, but he took up the struggle with greater energy than his predecessors. In 1074 he published an encyclical, absolving the people from their obedience to bishops who allowed married priests. The next year he enjoined them to take action against married priests, and deprived these clerics of their revenues. Both the campaign against priestly marriage and that against simony provoked widespread resistance.

His writings treat mainly of the principles and practice of Church government. They may be found under the title "Gregorii VII registri sive epistolarum libri".

He died an exile in Salerno; the epitaph on Gregory VII's sarcophagus in the city's Cathedral says: "I have loved justice and hated iniquity; therefore, I [now] die in exile."