Source: Timeline
July 19, 1917 Matthias Erzberger of the Catholic Center Party succeeds in securing a majority vote in the German Reichstag for a Peace Resolution calling for peace terms without changes in boundaries or economic impositions.
Gasparri cables Pacelli: “In the event that the conditions of the peace note present difficulties, Your Excellency should work in any event to obtain conditions that would truly be acceptable to the other side; otherwise everything is useless... Make the Chancellor reflect ...”
Source: www.Pacelli-Edition.de, Document No. 802
July 22, 1917 Pacelli cables Gasparri that newspapers are attributing Erzberger's Peace Resolution to Vatican influence; he leaves it to Gasparri whether to publish a denial; and he assures Gasparri that the Munich Nunciature played no role in the matter.
Source: www.Pacelli-Edition.de, Document No. 6052
July 27, 1917 Pacelli reports to Gasparri on his discussions with the new German Chancellor, Michaelis, about terms of the planned Papal peace proposal and the timing for announcing it.
English translation - Italian original and German summary at online Pacelli-Edition
July 27, 1917 Pacelli to Gasparri:
Your Most Reverend Eminence,
Following up on my respectful coded cable of the 25th, I am fulfilling my duty, upon returning to Munich, of giving Your Most Reverend Eminence a more particularized report of the discussions I had in Berlin about the peace proposals by the Holy See.
Arriving in the Capital on the 24th, I immediately had a long conference both with Mr. Michaelis, the new Reich Chancellor, and with Mr. Zimmermann ... After the usual pleasantries, I told them that the Holy Father and Your Eminence were left very satisfied by the most courteous welcome and the openness shown me by the Imperial Government, on the occasion of my first visit to Berlin, concerning the views of Germany on the principal questions that relate to the current conflict and to the way of ending it, and indeed that the Holy See would consider presenting, either immediately or this coming autumn (when the offensive will have ended and its ineffectiveness will be evident), to all or at least to the principal belligerent States, a peace proposal on the fundamentals, of which I gave copies to both the aforesaid Men of State in Italian, as well as in an exact German translation that I had taken care to have prepared. I added that, although these fundamentals had not yet been communicated to the other Powers, nonetheless the selfsame Holy See, based on information that is possible for It to obtain thanks to its admirable worldwide organization, believed able to consider not indeed certain, but seriously probable, that the proposal itself would be welcome. However, the Holy See, before proceeding to an official step with the various States, desired, out of a special regard toward Germany, which has shown itself more inclined toward peace than all the others, to know confidentially the thoughts of the Reich Government concerning the often-mentioned foundations. I concluded that Germany, showing itself conciliatory in a way to expedite peace, would add to military glory the merit of having given back to humanity a new era of civilization and prosperity, and would regain the sympathy of the whole world, while the new Chancellor would thus begin his exalted office under the best auspices...
Source: Historical Archive of the Secretariat of State (Holy See), Section for Relations with States, Vatican Secret Archives, AA.EE.SS., Stati Ecclesiastici, 1914-1921, pos. 1317, fasc. 470, vol. III, fol. 148r-151v, reprinted at www.Pacelli-Edition.de, Document No. 378.