However, his most important legacy is the First Vatican Council, convened in 1869, which defined the dogma of papal infallibility, but was interrupted as Italian nationalist troops threatened Rome.
Namun, warisan terpentingnya adalah Konsili Vatikan Pertama, yang diselenggarakan pada tahun 1869, yang mendefinisikan dogma infalibilitas paus, tetapi disela ketika pasukan nasionalis Italia mengancam Roma.