The modern history of the papacy is shaped by the two largest dispossessions of papal property in its history, stemming from the French Revolution and its spread to Europe, including Italy.

In 1793, a French diplomat in Rome, Nicolas Jean Hugon de Bassville, indulged in a provocative display of the tricolour, symbol of French anti-clerical republicanism. A Roman crowd attacked him and he died the next day. Four years later, when Napoleon reached as far south as Ancona in an advance on Rome, this incident remained a specific grievance for which France held the pope responsible - demanding and receiving 300,000 livres as compensation for Basseville's family.

In 1797 French Republican troops under the command of Napoleon Bonaparte invaded Italy, defeated the papal troops and occupied Ancona and Loreto. Pius VI sued for peace. The price of persuading the French intruder to head north again, agreed in the Treaty of Tolentino, was a massive indemnity, the removal of many works of art from the Vatican collections and the surrender to France of Bologna, Ferrara and the Romagna.

However, on 28 December of that year, a popular French general was killed in a riot outside the French embassy in Rome, thus providing a new pretext furnished for invasion by the French. French army units marched to Rome, entered it unopposed on and, proclaiming a Roman Republic, demanded of the Pope the renunciation of his temporal authority. Upon his refusal to do so, Pius VI was taken prisoner, and on February 20 was ultimately brought to the citadel of Valence in France where he died.

The new pope, Pope Pius VII, was at first conciliatory towards Napoleon. He negotiated the French Concordat of 1801 which reaffirmed the Roman Catholic Church as the major religion of France and restored some of its civil status, removing it from the authority of the Pope. While the Concordat restored some ties between France and the papacy, the agreement, especially as supplemented by the "Organic Articles" that Napoleon unilaterally promulgated after signing the Concordat, was slanted largely in favor of the state; the balance of church-state relations had tilted firmly in Napoleon Bonaparte's favor.

In 1804, Pius VII traveled to Paris to officiate at Napoleon's imperial coronation. On December 2, Napoleon crowned himself Emperor of the French in the Cathedral of Notre Dame, Paris, in the presence of Pope Pius VII. Claims that he seized the crown out of the hands of Pope Pius VII during the ceremony in order to avoid subjecting himself to the authority of the pontiff are apocryphal; in fact, the coronation procedure had been agreed upon in advance.

But by 1808 relations had deteriorated. The pope annoyed Napoleon by refusing to sanction the annulment of his brother Jerome's marriage and, perhaps more significantly, by not bringing the ports of the Papal States into the Continental System.

The result was that a French army occupied Rome in February 1808. In the following month another section of the papal states (the Marches) was annexed to the Napoleonic kingdom of Italy. Napoleon followed up these affronts by annexing in 1809 all that remains of the papal states, including the city of Rome, and by announcing that the pope no longer has any form of temporal authority. Pius VII responded by an immediate use of his spiritual authority, excommunicating Napoleon himself, albeit not by name, and everyone else connected with the annexation. Pius VII was soon thereafter arrested by French General Etienne Radet, acting on letters from Napoleon to his commanders in Italy ambiguously expressing consternation over the Pope's recalcitrance. The Pope would remain a prisoner of the French until February 1814.