The farce of Vatican I where Pius got himself coronated infallible by a rigged vote of pensioners living off his dime, causing ANOTHER split.A small split that created the "Old Catholic Church" from those who could not park their intellect and knowledge of history, at the door and except the fantasy of infallibility. I think it was mostly Germans. Dollinger, a famous Catholic historian of the time, could not accept it either.And what split is that? In fact, Vatican I began a period during the pope gained a degree of direct control over the Church unmatched since the 13th Century, unlike the Medieval popes, he did not have to rely on the authority of the State.
I think Pius wanted it to make himself feel better after losing temporal power.
The “Old Catholic Church” was never more than a splinter group. As for Pio Nono’s motivation, it was the shock of realizing that Italian Liberals were fanatics who would stop at nothing—and were liars. Jokingly he once said that he and Garibaldi were the only honest men in Italy. As i said above, the effect was to free strengthen the hand of the papacy. German nationalists, like Doellinger, did not like this, nor did liberals like Acton, although the latter did not follow his mentor out of the Church.