Giovanni Maria Mastai-Ferretti is one of the most interesting and complex individuals to ever become Supreme Pontiff of the Roman Catholic Church. He was born in 1792, during the French Revolution, lived through the Napoleonic conquests of Europe, and witnessed the unification of both Italy and the Prussian Empire. His pontificate included the proclamation of the dogmas of the Immaculate Conception and papal infallibility, the convocation of the First Vatican Council, the publication of the Syllabus of Errors, the beginnings of Catholic Action, and the development of the foreign missions. If you want an insight into the many interesting facets of the relationship between the Church and the world at the end of the 19th century, this book is for you. If you are interested in the fight of the Church against the great movements of Modernity: liberalism, Freemasonry, the Enlightenment, laicism, capitalism and communism, this book is worth reading. If the mention of Pius IX brings nothing to mind, you need to read this book. The author, Yves Chiron, is a professor of history and a member of the Society of the Ecclesiastical History of France. He has authored many works in his native French, including biographies of Padre Pio and Paul VI, and is the author of the Angelus Press title St. Pius X: Restorer of the Church.