The border with Hungary was drawn along a railway

In Bucharest, in August 1916, Brătianu sets pen to the secret treaty of 4/17 August — and Romania enters the war on the Entente's side: Transylvania, the Banat, Crișana, Maramureș and Bukovina, with the frontier on the Tisza.

The treaty of 4/17 August 1916 promises Romania Transylvania, the Banat, Crișana, Maramureș and Bukovina, plus a seat at the peace table; Article V bars it from a separate peace. Article IV draws the line in the plain: it joins the Tisza on a line with Algyő village, north of Szeged, then follows the river's thalweg to its Danube confluence. Eleven days later the proclamation of 28 August 1916 promises the army, in the source's English rendering, “a great and free Rumania from the Tisza to the Black Sea”. Two years of war later, on 1 December 1918, Alba Iulia votes the union — and the promise of 1916 becomes a file on the Paris table.

On 29 January 1919, in a Paris hall, Brătianu opens his file and reads “The Problem of the Banat” before the Supreme Council — the whole Banat, per the 1916 treaty, which Paris however deems void after the separate peace of 1918.

On 29 January 1919 Brătianu reads “The Problem of the Banat” before the Supreme Council: the whole Banat, per the 1916 treaty, with equal rights for every minority. On 18 March the experts propose splitting it anyway — two thirds to Romania, one third to the Serb-Croat-Slovene kingdom, cutting the Bega canal and leaving some 100,000 Romanians in the Yugoslav part. Inside the frontier committee the Americans propose a line 20 to 50 kilometres east of today's border and the Italians one some 100 kilometres east toward the Royal Pass; the Franco-British proposal wins, favouring Romania's economic and military advantage over ethnic lines; on 8 May 1919 André Tardieu adds a reason: the Satu Mare–Oradea main railway must stay Romanian.

On 2 July 1919, Brătianu rises from the conference table and leaves Paris rather than sign the minorities treaty — and on 12 September he resigns as prime minister.

Saint-Germain is signed with Austria on 10 September 1919 — Article 59 cedes Bukovina to Romania, Article 60 demands the minorities treaty. When the Supreme Council's ultimatum of 15 November orders Romania to sign “without commentaries, reserves and conditions”, the Văitoianu cabinet refuses and falls on 30 November. Alexandru Vaida-Voevod, prime minister from 1 December, unblocks Paris: on 9 December 1919 Romania signs the treaties with Austria and Bulgaria and the minorities treaty, with minimal concessions — and the hands that signed are disputed to this day: some sources name Nicolae Mișu and Vaida-Voevod; the Goga biography points to General Constantin Coandă.

On 4 June 1920, in the gallery joining the Grand to the Small Trianon, two minor envoys set pen to the unalterable text of 6 May — Apponyi had pleaded on 16 January, and now the bells are tolling in Budapest.

The Hungarian delegation receives the terms on 15 January; Apponyi speaks the next day before every major leader except Wilson — by then, Hungary's fate was already decided. In early March 1920 Lloyd George protests that the treaty consigns some 2,750,000 ethnic Hungarians, one third of the nation, to the successor states; by 7 March the frontiers are confirmed unchanged. The final text of 6 May answers 38 Hungarian notes and changes “not … a single word” of the territorial clauses; the Millerand cover letter promises only minor adjustments. On 31 May Budapest sends Ágost Benárd and Alfréd Drasche-Lázár to France; on 4 June they sign alongside Ion Cantacuzino and Nicolae Titulescu, Romania's delegates by royal decree — while bells toll in Budapest and silence falls.