Young Pompeo was given a rigorous upbringing at Monte Compatrum in the Tusculan hills east of Frascati, under the watchful eyes of his uncles Prospero and Cardinal Giovanni Colonna.

[3] In 1498, as a young man of eighteen, Pompeo fought alongside his uncle Prospero, Lord of Genazzano and Nemi, Duke of Traetto, Count of Fondi, against the traditional family enemies, the Orsini.

His uncle took Pompeo to Naples after the Orsini affair was settled, and introduced the young man to King Federigo I, whose fast friend he quickly became.

It was decided by Pompeo's uncles that he should enter upon an ecclesiastical career, so that he could succeed to the rich benefices and powerful offices enjoyed by Cardinal Giovanni.

[8] The Cardinal was not a disinterested philanthropist, for, though he increased the numbers and prestige of the Canons, his nephew also gained twelve benefices which were at the disposal of the Bishop to reward Colonna followers.

[10] In 1511, when rumours of the imminent death of Pope Julius II spread,[11] Pompeo and Antonio Savelli spurred the Roman population to rebel against the Papal authority.

[15] Pompeo was so angry that he even threatened to join the French, who had seized Bologna earlier in the year, but his uncle Prospero firmly dissuaded him from such wild designs.

Ferdinand provided Pompeo with money, and he proceeded through Germany to Bruxelles, where he engaged in discussions with Prince Charles, who was then Duke of Burgundy and an Austrian Archduke.

Immediately after his promotion, he was sent to Germany (Germania Superior), where he met the Emperor in Augsburg (Augusta Vindelicorum), and followed his court, inspecting the German cities and learning of their moral state.

The administrator also enjoyed the right to fill whatever benefices were vacant during his term, normally a privilege of the Bishop; this allowed him to reward his faithful followers and servants at no expense to himself.

Pope Leo died on Sunday 1 December 1521, aged 46, leaving the Papacy with debts amounting to 1,154,000 ducats, according to Giovanni Mattheo, the secretary of Cardinal Giulio de' Medici.

Around 25 October, Cardinal Numai received twenty-two votes, only four short of election,[48] but the Imperialists remembered well that he had taken his Degree at the Sorbonne, and that he was a personal friend and former Confessor of the French Queen Mother, Marie of Savoy.

Colonna's support was a puzzle for many outsiders, until he was named Vice-Chancellor, the office just vacated by the new Pope, and acquired the Medici palazzo in Rome (the Cancelleria Palace).

Cardinal Colonna was named Administrator of the diocese of Acerno in the Kingdom of Naples on 18 January 1524; he held the post until 23 June 1525, when a bishop was appointed.

On 23 June 1525, Cardinal Pompeo Colonna was named Administrator of the diocese of Rossano in the Kingdom of Naples, following the death of Bishop Juan Fonseca.

During his term as Viceroy of Naples, he was particularly unaccommodating with regard to a request of Cardinal Piccolomini in the naming of a Provost of S. Eusanio Forconese, preferring one of his own retinue from Rieti for the benefice.

[59] On 22 May, the League of Cognac was signed by Francis I (who was just released from his captivity following the Battle of Pavia), Pope Clement VII, the Republic of Venice, Florence, and the Sforza of Milan, specifically to destroy the Imperial hold over Italy.

[62] On 20 September, a force of 3,000 foot soldiers and 800 cavalry, led by Cardinal Pompeo Colonna, entered Rome by the Porta S. Giovanni.

At the same time, the famous Tyrolean condottiere Georg von Frundsberg, having collected a large band of Landsknechts, descended into the Po Valley, headed for Milan.

The terms involved the loss by the Papacy of Ostia, Civitavecchia, Pisa, Parma, Piacenza and Livorno; the payment of 200,000 ducats for the Landsknechten, and the restoration of the Colonna.

[74] A surprise skirmish took place on 31 January at Frosinone, in which the Imperial forces, in which Cardinal Pompeo Colonna was playing a military role, were bested.

At the end of April, Cardinal Pompeo Colonna and Ugo de Moncada wrote to Lannoy that they had prepared an insurrection in Rome for 10 May.

The Spanish-German army, numbering some 40,000 soldiers, reached Rome on Sunday 5 May, and that afternoon the Constable de Bourbon made the Convent of S. Onofrio his headquarters.

[84] The famous goldsmith Benvenuto Cellini, who was with the papal party and fled with Clement VII to the Castel S. Angelo,[85] claimed credit as the marksman, though the morning was foggy and the arquebus' accuracy is not great.

Camillo Colonna, the son of Cardinal Pompeo's eldest brother, led the street fighting as far as the Orsini stronghold at Monte Giordano.

A council was appointed, including Bemelberg (Frundberg's successor), the Abbot of Nagera (Fernando Marin, Commissary General of the Imperial Armies in Italy), Giovanni Battista Lodron, Juan de Urbina, Cardinal Pompeo Colonna, Vespasiano Colonna (Prospero's son), Girolamo Morone (the Sforza agent), Mercurino Gattinara (the Emperor's Grand Chancellor), and others.

This was an explicit part of the treaty which was being worked out between the Emperor and the Pope [95] Early in June it was reported that Cardinal Colonna was ill with 'the flux' (dysentery?

[100] The plan, nonetheless, was still being promoted by Alarcon, Nagera and Urbina in mid-July, as the solution as to who should take charge when the Pope departed Rome for Rocco di Papa or Salmonetta.

On 20 April 1529, Cardinal Pompeo was named Administrator of the diocese of Aversa in the Kingdom of Naples by Clement VII; he resigned upon the appointment of his nephew Fabio Colonna to the See on 24 September 1529.

[106] On 14 December 1530 the Cardinal was named archbishop of Monreale by Pope Clement VII, and was granted the pallium on 6 February 1531[107] He held the office until his death in 1532.