How did the final vote on papal infallibility take place at the First Vatican Council?

The final vote on papal infallibility at the First Vatican Council took place on July 18, 1870, after extensive debate. The council, convened by Pope Pius IX, ultimately defined papal infallibility as dogma.123

The process involved a decisive vote on July 13, where 451 council fathers voted in favor of the definition, 88 voted against, and 62 proposed amendments. Following this, the minority opposition left Rome. The final promulgation of the doctrine occurred on July 18, with 533 votes in favor and only 2 against.4

The doctrine, as defined in the dogmatic constitution Pastor Aeternus, states that the pope, as the successor of St. Peter, is preserved from error when he definitively teaches a doctrine concerning faith or morals that is to be believed by the entire church. This teaching power is exercised when the pope speaks ex cathedra, meaning "from his chair" as supreme teacher, intending to demand irrevocable assent from the whole church.53