Lateran Treaty
Negotiations for the settlement of the Roman Question began in 1926 between the government of Italy and the Holy See, and culminated in the agreements of the Lateran Pacts, signed—the Treaty says—for King Victor Emmanuel III of Italy by Benito Mussolini, Prime Minister and Head of Government, and for Pope Pius XI by Pietro Gasparri, Cardinal Secretary of State, on 11 February 1929. It was ratified on 7 June 1929. The agreements were signed in the Lateran Palace, hence the name by which they are known.
Millerand letter
The Alexandre Millerand Letter was written by French Prime Minister Alexandre Millerand and was an annex to the Trianon Treaty. It stated that the border amendments made by the Trianon Treaty were not final, and could be reviewed in the future. This give the Hungarian government the false impression that the treaty itself was only temporary, and so the delegation signed the treaty on June 4, 1920.