Pius VII had reigned as Pope for what was then considered a very long pontificate (he was elected in 1800). During his reign as Pope, the Catholic Church had faced, in the French Revolution and its aftermath, the most severe attack on its power and legitimacy since at least the Reformation - some might say since Constantine made Christianity the state religion of the Roman Empire.
During Pius VII's papacy, the cardinals had tended to divide into two groups, the zelanti and the politicani. The zelanti were more radically reactionary than the politicani and wanted a highly centralised Church and vehement opposition to the secularising reforms that had resulted in France from the Revolution spreading to the Papal States. The politicani, though anti-liberal, were much more moderate and favoured a conciliatory approach to dealing with the problems new ideologies and the incipient Industrial Revolution were creating. The leader of this faction was Pius VII's Secretary of State, Cardinal Consalvi, but the zelanti wanted a much less moderate pontiff and they set fervently on this task from the time of Pius VII's death.
The length of Pius VII's papacy had a significant influence because of the forty-nine electors who participated in the conclave, only Giulio Maria della Somaglia and Fabrizio Dionigio Ruffo were already cardinals when Pius VII was elected in 1800. Thus, forty-seven of the forty-nine electors had had no practical experience electing a Pope before this conclave.
A number of cardinals were thought at the beginning of the conclave as possible successors to Pius VII. Antonio Gabriele Severoli was at first seen as the most likely papabile, but the veto of Francis I, Emperor of Austria ruled him out when he looked to have a reasonable chance. Francesco Saverio Castiglioni then took over as the most likely candidate, but after a while it was realised he was quite close to Consalvi: thus, his name was crossed off quickly. The experienced Cardinal della Somaglia then had a turn as a possible candidate, but for some the mere fact that he had signed his letters "Citizen Somaglia" during the occupation of the Papal States by Napoleon I of France ruled him out.
It was only then that the eventual winner, Vicar of Rome Annibale Cardinal della Genga, appeared due to the proposal by the zelanti. Whilst his tall, ascetic look and reactionary reputation was not an attraction for the politicani, but the fact that he was seemingly at death's door seemed an attraction for those cardinals by now desperate for a resolution of the conclave. As a result, Della Genga was elected on the 28th of September and took the regnal name Leo XII.
Leo XII was crowned as Pope on 5 October 1823.
|Veto used||by Emperor Francis I of Austria|
|DECEASED POPE||PIUS VII (1800-1823)|
|NEW POPE||LEO XII (1823-1829)|