Also from the Vatican Insider page of La Stampa mentioned by Mark below (the picture at right is of Garibaldi, not Mark) is this piece about a conference at the Pontifical Lateran University about the Christian roots of Italy as nation-state. The aim of the conference was to study “the contribution of Christianity to the formation of Italian identity through the work of the Church[.]” It may be somewhat revisionist to claim that the Roman Catholic Church was truly in support of Italian unification. Pope Pius IX was in fact rather hostile to the idea, and not without understandable political reasons given the fortunes of the Papal State after 1861.
Be that as it may, I found the following paraphrased statement by historian Msgr. Cosimo Semeraro (as reported in the story) to be a nuanced and sensible characterization:
Undoubtedly unity took place in the wake of a bitter dispute between Savoy and the Papal State, and was achieved against the interests of the Church itself, Msgr. Semeraro acknowledged Nevertheless (Piedmontese prime minister) Cavour “also began to become aware of the universal value of Rome and the papacy”. Therefore, “The insistence of Cavour for the proclamation of Rome as the capital in 1861 reflects his awareness that the future of the new state had to necessarily pass through a reconciliation with the Holy See”.
To sum it up all, he is convinced that the contribution of Catholics was actually crucial, both in terms of “social and political initiatives of Italian Catholicism to address economic imbalances and social inequalities” and in historical circumstances like World War I, when “large masses, especially peasants” were made more familiar with “a state still suffering from the markedly elitist dimension of its beginnings”.