This is a historical question. I'm interested in the earliest instance that the Catholic Church (whether by the Vatican or by a bishop) accepted a Protestant baptism for a catechumen (a convert), thus the Confirmation sacrament did not have to be preceded by even a conditional sacrament of Baptism. Was this before Trent, after Trent but before Vatican II, or only after Vatican II? Which bishop did it first?
What was the occasion, the rationale? Was the original rationale back then the same as the current rationale? Maybe the council of Trent itself addressed this? Was there a document?
A related question that does not need to be answered, but only to sharpen the issue to be addressed in the rationale. By the same rationale to accept Protestant baptism for catechumens, what if these same Protestants did NOT become catechumens? Was it possible for them to be saved (since baptism is only a factor) while remaining in their Protestant churches because the Catholic church teaches that by any valid baptism they would have received the Trinitarian life (born again)?
If the answer is yes, wouldn't this contradicts the (older) Catholic notion that Protestants who denied certain Catholic-specific dogmas were not saved? Or perhaps only Protestants who through no free and conscious act of denials were saved? For example: they live in a country whose prince is Protestant (cuius regio, eius religio) so they were not free to convert to the Catholic Church, OR they were open minded about these dogmas?