Leo, the name of twelve popes, of whom the following are the most important.

I. Leo I., Saint, Surnamed The Great

Surnamed The Great I. Leo I. Saint, born of Tuscan parents in Lome about 390, died there in November, 461. He was employed by Popes Zo-sinms, Celestine L, and Sixtus III. on the most important missions. In 418 he was sent to the churches of northern Africa to unite the bishops against the spread of the Pelagian doctrines; and he displayed great activity in combating the Nestorian heresy. When the dissensions between the imperial commanders in the West, Aetius and Albinus, left Gaul and Italy exposed to the attacks of the barbarians, Leo was sent by the emperor Valentinian 111. to appease the quarrel, and had just succeeded in his mission when Sixtus 111. died in the summer of 440, and Leo was unanimously chosen his successor. His first efforts as pope were directed toward restoring harmony and discipline among the churches of Africa, annulling fraudulent episcopal elections in Gaul, enforcing celibacy among the clergy, and suppressing the immorality charged on the Manichaeans of Italy. In 445 he held a council in Rome to judge the appeal of Celidonius, bishop of Be-sancon, who was declared innocent and restored to his see; and St. Hilary, archbishop of Aries, who had deposed him, was for a time deprived of his metropolitan jurisdiction.

In Spain he approved of the execution of Pris-cillian, convicted of magic and immorality, and put to death by the usurper Maximus, and he procured the condemnation of Priscillian-ism by a national council of Spanish bishops. Eutyches, condemned for heresy at Constantinople in November, 448, made an appeal to Leo which was supported by the emperor Theodosius 11. This led to the convocation at Ephesus, in 449, of what is known as the "robber synod," in which the partisans of Eutyches, protected by the imperial troops, excommunicated Leo, and caused or hastened the death of Flavian, patriarch of Constantinople. These violent proceedings were cancelled by the general council of Chalcedon in 451, over which Leo's legates presided, and in which his letter was accepted as the expression of orthodox doctrine. In -152, at the invasion of Italy by the Huns under Attila, the emperor Valentinian having taken refuge in Lome, and his general Aetius having abandoned Italy to her fate, Leo with two senators went to meet Attila near Mantua, and persuaded him to accept a pecuniary ransom from the Romans, and to retire beyond the Danube. In 455, Genseric and an army of Vandals having come to Lome at the invitation of the empress Eu-doxia, the mediation of Leo could only obtain a promise that the lives of the citizens should be spared, together with three churches, which served as an asylum while the rest of the city was sacked.

All the treasures of Rome having been carried to Africa with her chief citizens, the pope devoted himself to redeeming the captives and relieving the manifold distress of his flock. He also used his influence with the court of Constantinople to quell the religious troubles caused in Egypt and Syria by the partisans of Eutyches. - Besides a large collection of sermons, there remain 173 letters of St. Leo on ecclesiastical matters addressed to contemporary sovereigns, bishops, and councils. Quesnel attributed to him the treatise De Vocations Gentium, considered by some to belong to St. Prosper, and by others to St. Ambrose. Of the numerous editions of his works, the principal are those by Pasquier Quesnel (2 vols. 4to, Paris, 1675), Cacciari (2 vols, fol, Rome, 1753-5), and Ballerini (3 vols. fob, Verona, 1755-'7). See also Dumoulin, Vie et religion de deux bons papes, Leon I. et Gregoire I. (Paris, 1650); Maimbourg, His-toire du pontificat de St. Leon (1687); Arendt, Leo der Grosse und seine Zeit (Mentz, 1835); Perthel, Pabst Leo's I. Leben und Lehren (Jena, 1843); Saint-Cheron, Histoire du pontificat de St. Leon le Grand et de son siecle (2 vols., Paris, 1840).

II. Leo III., Saint

Saint II. Leo III., born in Pome about 750, died there, June 11, 810. He was educated in the monastic school attached to the Lateran palace, was cardinal-priest of Santa Susanna, and distinguished for his learning and eloquence, when he succeeded Adrian I., Dec. 25, 795. Ho immediately wrote to Charlemagne to renew the relations which existed between the latter and Pope Adrian, confirmed the title of patricius, senator or protector of Rome, bestowed upon Charlemagne's father Pepin by Pope Stephen III., and received in return a portion of the spoils Avon from the Avars by Charlemagne. At the time of Leo's election Rome was visited by Offa, king of the Mercians, who increased the revenues of the English college founded at Rome by Ina (died 728), and which was supported by a tax originating with these princes, which afterward received the name of " Peter pence." On April 25, 799, while present on horseback at the solemn procession in honor of St. Mark, Leo was attacked by an armed band led by two priests, Paschal and Campolo, nephews of Adrian I., who, after attempting to put out his eyes and cut out his tongue, imprisoned him in a neighboring convent.

Having been delivered by the citizens, he took refuge in Spoleto, and thence went to Paderborn, where Charlemagne received him with honor, and gave him a numerous escort of bishops, counts, and armed men to accompany him on his return to Rome. The two priests who had made the assault on him were then tried and banished to France. Toward the close of the year 800 Charlemagne, after expelling the Saracens from the Balearic islands, went to Rome, where a council of bishops examined the charges brought against Leo by the exiled assassins, and declared the pope's innocence. On Christmas day Charlemagne was anointed emperor of the West by Leo. In 804 the pope visited the emperor at Aix-la-Chapelle, and prevailed on him to restore the full liberty of canonical elections, to prevent those called chorepiscopi from exercising episcopal powers or conferring holy orders, to forbid churchmen from bearing arms, and to enforce the obligation of residence for bishops. The council of Aix-la-Chapelle in 809 having approved the custom established in Spain and followed by the Frankish monks of Palestine, of inserting the words Filioque in the Nicene creed, the decision of the council was submitted in 810 to Leo, who advised the discontinuance of the custom.

He had the Nicene creed engraved in Greek and Latin, without the addition Filioque, on silver tablets, which were hung up near the Confession of St. Peter. In 815 a new conspiracy was discovered, and its authors were put to death. The sentence and its hasty execution were censured by the new emperor Louis le Debonnaire. In 816, an earthquake having ruined several towns in Italy, and thrown down a church in Rome, Leo in order to propitiate the divine wrath established the solemn litanies and processions known as the Rogations. Leo III. is praised by his contemporary Anastasius the Librarian for his munificence in building and adorning churches. Thirteen letters of this pontiff are extant in Labbe's Concilia, vol. vii. Hermann Conring published his Epistolae ad Carolum Magnum (4to, Helmstedt, 1647).

III. Leo IV., Saint

Saint III. Leo IV., born in Rome about 800, died there, July 17, 855. He was educated in the monastery of San Martino, became a member of the community, was selected by Gregory [V. as one of his domestic prelates, and created a cardinal by Sergius II. He was unanimously elected pope Jan. 30, 847, without the customary notice being sent to the emperor, because the city was threatened by Saracen pirates. They had just ravaged the environs of Rome, and sacked the basilicas of St. Paul without the wall and St. Peter on the Vatican, carrying away the silver and gold which decked St. Peter's tomb. Leo, aided by the emperor, enclosed the Vatican with fortifications. (See Leonine City.) In 849, while the work was still in progress, the Saracens landed a great force at Ostia. The pope armed every man in Rome and the neighborhood, obtained auxiliary troops from Gaeta and Naples, and sallied forth at their head in his priestly robes. A fearful storm came to the aid of the Romans; the Saracen fleet was scattered or wrecked, and the invaders were utterly routed.

The rich booty recovered by the victors helped the pope to complete the entire circuit of the walls of Rome. The city of Porto was also rebuilt by Leo for purposes of defence in 852, and peopled by a colony of Corsicans, whom the Saracens had driven from Bastia. On Dec, 8, 853, he held in Rome a council of 67 bishops, in which canons were enacted for the discipline of the clergy and the instruction of the people in the knowledge of gospel truth. Two letters of Leo's are extant in Labbe's Concilia, vol. viii.

IV. Leo X. (Giovanni De' Medici)

IV. Leo X. (Giovanni De' Medici), born in Florence, Dec. 11, 1475, died in Rome, Dec. 1, 1521. He was the second son of Lorenzo the Magnificent, destined for the church at his birth and before his eighth year appointed by Louis XL of France abbot of Font-Douce, and by Pope Sixtus IV. abbot of Pas-signano and prothonotary apostolic. At 13 he was created cardinal by Innocent VIII., whose son, Francesco Cibo, had married in 1487 Madalena, Giovanni's sister. No pains were omitted by Lorenzo to make his son worthy of his rank in the church. He graduated in theology and canon law at the university of Pisa, assumed for the first time the insignia of the cardinalate March 9, 1492, and went immediately to Rome, whence he was recalled to Florence a few weeks afterward by the death of his father. He fixed his residence there as legate of the holy see, opposed the election of Alexander VI. in August, 1492, and then returned to Florence. In 1494 he and his brothers were expelled by the citizens, and after living five years an exile and fugitive, he quitted Italy in 1499, and visited Germany, the Netherlands, and France, seeking everywhere the acquaintance of the learned.

He returned to Rome in 1503, and lived there in retirement, making his house the resort of the most distinguished artists and men of letters in Italy. On the accession of Julius II. he was employed in the most important affairs. In 1506 he was appointed governor of Perugia, and subsequently legate of Bologna and commander of the papal troops in league with Spain against the French in Italy. In this capacity he was present at the battle of Ravenna, April 11, 1512, and was taken prisoner, but allowed to escape. The French having been driven out of Lombardy, Cardinal de' Medici employed the Spanish arms to reinstate his family at Florence. He was elected to succeed Julius II., March 11, 1513, received priest's orders March 15, was consecrated bishop on the 17th, was crowned on the 19th, and took possession of the Lateran April 11. Louis XII., who had been excommunicated and whose kingdom had been laid under an interdict by Julius II., was more than ever bent on conquering Lombardy. In March, 1513, he had signed at Blois a treaty with the Venetians, by which they promised to aid him in obtaining possession of Milan. The new pope instantly formed a counter treaty with Henry VIII., signed at Mechlin April 5, to which the emperor Maximilian, Ferdinand of Aragon, and the Swiss cantons acceded, and which resulted in the defeat of the French at Novara, June 6. This warlike activity of Leo X. seemed in contradiction to the policy announced on the day after his election to King Sigismund I. of Poland, to whom he wrote to urge him to make peace with Albert of Brandenburg, alleging that he was sending legates to all Christian nations to dissuade them from making war on each other.

Before his coronation, too, he chose as his secretaries the illustrious scholars Bembo and Sadoleto, and bestowed his first care on reconstructing the Roman gymnasium or university, founded by Eugenius IV., revived and liberally endowed by Alexander VI., and neglected by the warlike Julius II. In 1514 it already counted 100 professors, the most eminent scientific body in Europe, teaching every branch of sacred and profane science, including medicinal botany for the first time. In 1513 Leo purchased on the Esquiline hill a large property on which he founded the Greek institute, and established a Greek press, encouraging at the same time the culture of all the oriental languages, and paying out of his own purse for the printing of Sante Pagnino's version of the Bible, and of Piero Valeriano's key to Egyptian hieroglyphics. He also enlarged the patronage extended to the fine arts by Julius II. He obtained the release from prison of the conspirators against his own family at Florence, called to Rome and protected there Piero Soderini their chief, as well as Machiavelli, and restored to favor and public life the Colonnas, disgraced under his predecessor.

He reopened the fifth general council of Lateran, April 27, 1513, with great magnificence (see Lateran, Councils of), and declared it to be his intention to continue its sessions until the establishment of a general peace among the princes of Christendom. He made his brother Giuliano de' Medici general of the papal armies, his nephew Lorenzo governor of Florence, and his cousin Cardinal Giulio de' Medici (afterward Clement VII.) archbishop of that city. At the same epoch King Emanuel of Portugal sent him a splendid embassy to offer him the first fruits of Albuquerque's conquests in the East Indies; and Leo in return conferred on Emanuel the investiture of the conquered countries. Louis XII. after the battle of Novara was reconciled with the pope, who induced him to become the ally and brother-in-law of Henry VIII., and agreed not to oppose by open force his pretensions to the duchy of Milan. Louis secretly pledged himself to expel the Spaniards from Naples; and a matrimonal alliance was arranged between the pope's brother Giuliano and Fili-berta of Savoy, aunt of the duke d'Angouleme. The latter prince, on his accession as Francis I., Jan. 1, 1515, assumed the title of duke of Milan, and gained on Sept. 13 the memorable victory of Melegnano (Marignano). This was followed by a treaty with the pope, who gave up to Francis Parma and Piacenza, Bologna being annexed to the Papal States, and the authority of the Medici reestablished in Florence. Leo and Francis met in Bologna in December, 1515, and agreed upon a concordat, afterward promulgated in the Lateran council, March 16, 1517. By this the king repealed the pragmatic sanction of Bourges (1438), guaranteed to the pope the collection of annates and tithes, and obtained the right of nomination to all episcopal sees and principal benefices in France. Francis vainly interceded for the duke of Urbino, who, guilty of rebellion against Julius II. and Leo himself, had killed with his own hand in the open street Cardinal Alidori, archbishop of Pavia. The duchy of Urbino was subsequently bestowed on Lorenzo de' Medici, the pope's nephew, after whose death it reverted to the church.

Siena was also annexed; but the measures adopted for this purpose gave rise to a conspiracy against the life of the pontiff, in which Cardinal Petrucci, whose family were sovereigns of Siena, and several other members of the sacred college were implicated. Petrucci was strangled in prison, June 3, 1517, and the others were condemned to pay enormous fines. In order to bind the college of cardinals more securely to his person, Leo created 31 new cardinals, most of whom were Florentines. The treaty of Noyon, concluded between France and Spain, Aug. 13, 1510, was intended to be a definitive settlement of the affairs of northern and southern Italy, in direct opposition to the pope's policy. Leo endeavored to counteract this settlement by the treaty of London, Oct. 20. But the emperor Maximilian by becoming a party to both defeated Leo's purpose; while the treaty of Fribourg made by Francis I. with the Swiss cantons, Nov. 20, deprived the pope of his most faithful allies. During the treacherous peace which followed this settlement and the conspiracy of Petrucci, Leo and his cardinals displayed their taste for magnificence and the encouragement of literature and art.

The council of the Lateran was closed with great solemnity in 1517; and a bull was published urging all Christian princes to form a league against the Turks, and granting indulgences to all who joined in the crusade, or contributed toward paying its expenses. The building of the new basilica of St. Peter's was pushed forward; and the lavish expenditure of the pope having exhausted his treasury, an indulgence was offered to all who would give money toward the construction. This occasioned the quarrel in Germany between the Augustinian monk Martin Luther and the Dominicans, and led step by step to the reformation. Leo, who looked upon the first movements of this great religious revolution as a quarrel between monks, who also admired Luther's genius and wished to conciliate him, summoned him, Aug. 7, 1518, to appear in Rome within GO days; but irritated him by ordering the legate at the imperial court to examine him in Germany, and, if found heretical in doctrine and refractory, to send him a prisoner to Rome. The compromise effected by the conference of Augsburg only made Luther appeal from the pope misinformed to the pope better informed; and when Leo's bull of Nov. 9, 1518, defined the right of the Roman pontiff to grant indulgences and explained their nature, Luther appealed from the bull to a general council.

At the solicitation of the kings of Hungary and Poland, whose dominions were continually threatened by the Turks, he sent the most eminent among his cardinals to the European courts to advise the formation of a common league against the foes of Christendom. He submitted to the sovereigns the plan of a combined attack by land and sea against the Turkish empire, he himself promising to sail from Ancona with 100 armed vessels to join the allied fleets. At the same time he proclaimed a general truce for five years, which was accepted by the sovereigns; but nothing more than a defensive league was effected between England, France, and Spain, with the pope at its head, which served to check temporarily the advance of the Turks. Leo made a second effort to conciliate Luther, and a conciliatory letter from Luther was answered by a pacific one from Rome. But public theological discussions revived the zeal of the reformer, and a bull was at length issued, June 15, 1520, condemning his writings as heretical. This Luther burned publicly at Wittenberg, Dec. 10. In 1521 the cause of the American Indians was brought to Leo's tribunal by both Franciscans and Dominicans, the former endeavoring to justify the Spanish system of reducing them to slavery.

Leo condemned the system, and employed his utmost endeavors to prevail on the king of Spain to repress it. In April, 1518, Leo gave his nephew Lorenzo, duke of Urbino, in marriage to a relative of the French king, and in return had to surrender the cities of Reggio and Modena. From these nuptials sprung Catharine de' Medici, queen of France. At the death of the emperor Maximilian, Jan. 12, 1510, Leo sent his own relative Cardinal Orsini to Francis I. to urge him to oppose the election of Charles of Spain, and, if possible, to secure the nomination of some inferior German prince. Orsini failed in his main purpose; Francis used his utmost endeavors and even open bribery, but only to secure the imperial crown for himself. Charles V., however, was elected emperor, June 28, and immediately demanded the pope's permission, as the public jurisprudence of the age required, to retain his Spanish possessions together with the imperial title. The pope having assented in spite of the remonstrances of the French king, the latter determined on war. It appears certain that Leo resolved at this conjuncture to execute Julius II.'s project of expelling from Italy both French and Spaniards, by taking advantage of the dissensions between the two monarchs.

He sent 150,000 gold crowns to Switzerland, and obtained a body of 6,000 Swiss auxiliaries; proposed to Francis I. to unite with him in an attack upon the kingdom of Naples; stipulating that Gaeta and the whole Neapolitan territory north of the Garigliano should be given to the church, that the remainder should be held for the second son of Francis, then an infant, and that an apostolic nuncio should govern for him till his majority. Francis meanwhile permitted the pope's Swiss auxiliaries to pass through the Milanese to the Romagna and the march of Ancona. Perugia was at this time forcibly annexed to the Papal States, and an attempt was made on Ferrara. Francis, divining the pope's real design, broke off the pending negotiations, and Leo openly united his forces with those of the emperor for the avowed purpose of wresting from the French the duchy of Milan and Genoa. By a treaty concluded with Charles V., May 8, 1521, Francesco Sforza was to be restored to his dominions, Parma and Piacenza were to be given back to the church, and the emperor was to aid the pope in annexing Ferrara, and to bestow the duchy of Civita di Penna in the kingdom of Naples on the son of the late duke of Urbino. The treaty was not made public till July 8. Prospero Colon-na with the Spaniards from Naples joined the papal forces at Bologna, crossed the Po at Casalmaggiore, and joined the Swiss, whose countrymen in the French service now deserted to the papal standard.

After a series of successes the allied army entered Milan Nov. 19; Parma and Piacenza were next occupied; but the duke of Ferrara defended his dominions to the last extremity against the spiritual and temporal arms of the pontiff. Leo received the intelligence of the capture of Milan and the recovery of Parma and Piacenza on Nov. 23. Amid the rejoicings consequent on these events he felt a sudden indisposition on the 24th, which excited no alarm, and died unexpectedly on Dec. 1, it is said without the sacraments of the church. His death has been by some writers attributed to poison; but nothing certain about its cause or manner is found in authentic contemporary accounts. - The character of Leo has been judged with more prejudice and discrepancy than that of almost any other person known in history. He has been accused of political insincerity, of adding treachery to injustice in his annexation of neighboring states, of an inordinate anxiety for the aggrandizement of his family, and of many failings which, however readily pardoned in a great prince, become odious in a Christian priest.

But whatever estimate we form of his foreign policy, it must be acknowledged that he governed his own subjects with wisdom and justice, and his reign was long gratefully remembered by the Romans as an era of happiness and prosperity. Engaging and affable in manners, gay or dignified as occasion demanded, and gifted with great powers of conversation, he charmed all with whom he came in contact. His private life both before and after his elevation to the throne was chaste and decorous. He was generous to excess, magnificent in his tastes, passionately fond of the chase, but temperate in the pleasures of the table. Though not a profound scholar, and accused of neglecting the studies best fitted to his station, he was well versed in the lighter branches of literature and a proficient in the art of music. He delighted above all things in the society of artists, poets, and learned men. He increased the Vatican library, and restored the celebrated library of his family (the Lau-rentian at Florence), which had been plundered and dispersed at the time of their expulsion.

He employed Michel Angelo and Raphael in the execution of some of their greatest works. His munificence might well entitle the reign of Leo X. to rank as the golden age of Italian art and letters. "Happy is it for the world," says Roscoe, " when the pursuits of such individuals, instead of being devoted, through blind ambition, to the subjugation or destruction of the human race, are directed toward those beneficent and generous ends which, amid all his avocations, Leo the Tenth appears to have kept continually in view." See Audin, His-toire de Leon X. (2 vols. 8vo, Paris, 1844), and Roscoe's "Life and Pontificate of Leo X." (6th ed. revised, 2 vols. 8vo, London, 1853).

V. Leo XII. (Annibale Della Genga)

V. Leo XII. (Annibale Della Genga), born in the territory of Spoleto, Aug. 2, 1760, died Feb. 10, 1829. Before his elevation to the pontificate he was papal nuncio at several German courts, and was sent to France on a special mission by Pius VII., whom he succeeded in the papacy, Sept. 28, 1823. He governed the church with a firmness which involved him in disputes with France and Austria, and administered the affairs of his temporal dominions with great zeal for the good of his subjects. He exerted himself to suppress brigandage and mendicity, promote education and literature, and suppress secret societies. He published a jubilee for the year 1825, and in a circular letter to the Christian nations attacked Bible societies. He entered into negotiations with the republics of South America for the purpose of filling up the many sees left vacant during their wars with Spain; organized in a most efficient manner the Sapi-enza university in Rome, and regulated its five faculties of theology, lawr, medicine, philosophy, and philology; increased the number of professors, and raised their salaries.

He manifested the design of reforming thoroughly church and state, and published in October, 1824, a motu proprio or decree reorganizing the administration of the Papal States. He corrected abuses in the convents and monasteries of Rome, and established order and security by means of a good police.