Pope St Pius X and the fight against Modernism


After having read Pascendi Dominici Gregis and The Oath Against Modernism, I’m left wondering how and why the Modernists seem to have won. Vatican II saw many clergy break their oath against the Modernist heresy. In fact, they openly supported the Modernist agenda and celebrated its apparent victory over the Traditionalists (read: the Church).

One thing that has stuck in my head about the whole Vatican II debacle is if every clergyman involved was an oathbreaker and a heretic (Modernism is heresy) and heretics are automatically excommunicated (per Canon Law), how were any of them able to retain their offices and authority? Would this not mean that every clergyman who teaches the Modernist point of view excommunicated himself by being a formal heretic? Would this not also mean that Vatican II and everything that came from the Magisterium since has been invalid since not one of the Modernists should have been able to hold any office?