No. The Council of Trent did not create the Latin Mass, and neither did Pope St. Pius V. The Roman Rite was already centuries old when they took it up; what they did was codify what existed, not compose it. The simplest way to say it: Trent received the Mass and handed it on.

By the sixteenth century the Roman Rite — with its Canon already witnessed in St. Ambrose around the year 390, its calendar built up over a millennium, its propers and ceremonies — had been prayed essentially intact for many generations across the Latin West. Local diocesan variants had multiplied; some were innocent customs, some carried real abuses. Trent (1545–1563) called for a careful pruning and a return to the Roman use as it had been, and delegated the work to the Pope.

In 1570 Pius V promulgated the resulting Missal with the bull Quo Primum. He did not invent its contents; he standardized them. And here is the fact that quietly refutes the slogan: Quo Primum expressly grandfathered any rite or use of at least two hundred years’ standing. The Ambrosian use of Milan, the Mozarabic of Toledo, the Dominican, the Carthusian, the Carmelite, the use of Lyon — all were left free to continue. Trent did not impose one uniform rite on everyone; it preserved the ancient ones.

So the Missal is Tridentine in promulgation but Roman in substance. (A note in honesty: Quo Primum’s “in perpetuity” language is sometimes pressed to argue no later pope could ever change the Missal — a contested polemical reading we do not lean on. The solid, sufficient point is the grandfather clause and the plain fact: codified, not created.)