In an interview posted 12-31-14, SSPX first assistant, Fr. Niklaus Pfluger, falsified why Archbishop Lefebvre retracted his May 5, 1988 agreement with modernist Rome. Fr. Pfluger stated that Archbishop Lefebvre “signed in 1988, two years after the scandal of Assisi, an accord that he denounced for the sole reason that he was convinced that Rome would not respect the accords (Postponed episcopal consecrations to August 15th).” 

Parenthetical explanation in the original; bold emphasis added. Quoted from an interview by Der Gerade Weg, an SSPX magazine in Germany. (English translation)

The truth is that Archbishop Lefebvre withdrew his signature on May 6, 1988 because Rome had not converted. During his Episcopal consecration sermon less than two months later, Archbishop Lefebvre explains his reason for changing his mind regarding the May 1988 protocol. He starts out posing a question from a hypothetical person who does not understand the situation:

“And why, Archbishop, have you stopped these discussions which seemed to have had a certain degree of success?”  

[The Archbishop Lefebvre answers this question:] Well, precisely because, at the same time that I gave my signature to the Protocol, the envoy of Cardinal Ratzinger gave me a note in which I was asked to beg pardon for my errors.  But if I am in error, if I teach error, it is clear that I must be brought back to the truth in the minds of those who sent me this note to sign. “That I might recognize my errors” means that, if you recognize your errors we will help you to return to the truth. What is this truth for them if not the truth of Vatican II, the truth of the Conciliar Church?  Consequently, it is clear that the only truth that exists today for the Vatican is the conciliar truth, the spirit of the Council, the spirit of Assisi.  That is the truth of today.  But we will have nothing to do with this for anything in the world!

That is why, taking into account the strong will of the present Roman authorities to reduce Tradition to naught, to gather the world to the spirit of Vatican II and the spirit of Assisi, we have preferred to withdraw ourselves and to say that we could not continue. It was not possible. We would have evidently been under the authority of Cardinal Ratzinger, President of the Roman Commission, which would have directed us; we were putting ourselves into his hands, and consequently putting ourselves into the hands of those who wish to draw us into the spirit of the Council and the spirit of Assisi. This was simply not possible.

This is why I sent a letter to the Pope, saying to him very clearly: “We simply cannot accept this spirit and proposals, despite all the desires which we have to be in full union with you. Given this new spirit which now rules in Rome and which you wish to communicate to us, we prefer to continue in Tradition; to keep Tradition while waiting for Tradition to regain its place at Rome, while waiting for Tradition to reassume its place in the Roman authorities, in their minds.”  This will last for as long as the Good Lord has foreseen.

It is not for me to know when Tradition will regain its rights at Rome, but I think it is my duty to provide the means of doing that which I shall call “Operation Survival”, operation survival for Tradition. Today, this day, is Operation Survival. If I had made this deal with Rome, by continuing with the agreements we had signed, and by putting them into practice, I would have performed “Operation Suicide”.

June 30, 1988 sermon, bracketed note and emphasis added.

Archbishop Lefebvre signed the protocol at 4:30 p.m., on May 5, 1988. Biography of Archbishop Lefebvre, by Bishop Tissier, p.554. Archbishop Lefebvre then spent a sleepless night, during which he composed his retraction letter. He declared: “Oh! How I wanted morning to come so that I could give Fr. du Chalard my letter of retraction which I had written during the night [of May 5, 1998].” Id., p.555.

Here is how Bishop Tissier recounts what Archbishop Lefebvre did on May 6, 1988:

The following day, after Mass and Prime, he finished off his letter and put it in an envelope which he showed to Fr. du Chalard at breakfast: ‘Father, before leaving, it is essential that this letter be taken to Cardinal Ratzinger. It’s a little bomb.’

Id.

Thus, it is clear from Archbishop Lefebvre’s own words that he realized within hours of signing, that he made a big mistake causing him a sleepless night during which he wrote his rejection of the practical agreement with modernist Rome.  He never wavered thereafter from his determination to not make an agreement with Rome until Rome comes back to the Church’s traditions and Faith.