July 15^th/28^th - Austro-Hungarian Monarchy declares war to Serbia
July 17^th/30^th - Entente representatives announce to the Romanian government the agreement of their countries regarding the unification of Transylvania with Romania, in exchange for Romania's participation in war against the Central Powers.
July 18^th/31^st - Message of German emperor William the 2^nd to king Charles the 1^st, demanding that Romania fulfils its obligations towards the Central Powers (1883, Oct. 18/30, Vienna. Signing, in secrecy, of the Romanian - Austro - Hungarian Alliance Treaty, joined by Germany that very day).
July 19^th/Aug. 1^st - Germany declares war to Russia. The general alliance system connecting the great powers unleashed world war one.
July 21^st/Aug. 3^rd - The Crown Council held at Sinaia rejected the demand of king Charles the 1^st to join the Central Powers and decided to adopt a policy of military neutrality.
Sept. 18^th/Oct. 1^st - Russo-Romanian secret Convention, engaging Russia to defend Romania's territorial integrity and the recognition of its rights over the Austro-Hungarian Territories inhabited by Romanians in exchange for a favourable neutrality of Romania ("Sazonov-Diamandi Agreement).
Sept. 27^th/Oct. 10^th - The death of King Charles the 1^st.
Sept. 28^th/Oct. 11^th - Ferdinand the 1^st, nephew and successor of Charles the 1^st, ascended to the throne.

1916

Aug. 4^th/17^th - Bucharest. Signing of the Alliance Treaty between Romania, on the one hand, and France, Great Britain and Italy, on the other. Among the conditions for Romania entering the war on Entente's side, Romania's demands were to be fulfilled.

Battle plans

According to interlude plans, the Russian troops would begin the offensive at the same time with the Romanian ones. The Anglo-French troops would land at Salonik, in order to stand against Bulgaria, which intended to attack Romania. These plans never came through, as the Allies' Salonik actions were overcome by a strong German-Bulgarian offensive, while the Russian troops arrived too late. As a consequence, the Central Powers troops occupied two thirds of the Romanian territory. With the help of the Russian troops the front was stabilised, at the beginning of January 1917, on the Siret River, the Danube and the St.George branch.

The 1917 campaign

In the free territory of Moldavia, from January to May 1917, the Romanian army was endowed with equipment similar to that of the enemy. A French military mission (led by General Henri Mathias Berthelot) and the warfare facilities from France and England changed the condition of the Romanian army. Two Romanian armies were organised, including approximately 400,000 men, joined by three Russian armies reaching almost 1,000,000 men. Thus the Romanian offensive of Marasti (11^th of July), led by General Alexandru Averescu, and that of generals Constantin Cristescu and Eremia Grigorescu of Marasesti (1^st - 24^th of July) thwarted the German plans to occupy Moldavia and conquer the Odessa port.

Romania in 1918

Oct.-Nov. 1917 - The Russian communists gripped power.
Jan. 27^th - Conclusion of the Brest - Litovsk Peace Treaty between Austro-Hungarian Monarchy and the Ukraine.
Feb. 18^th - Conclusion of the Brest - Litovsk peace between Soviet Russia and Germany.
March 5^th - Signing at Buftea (close to Bucharest) of the preliminary Peace Treaty between Romania and the Central Powers, on whose basis began at Bucharest, on the 9^th of March, the talks for peace making.
Apr. 24^th - The Bucharest Peace Treaty, between Romania, on the one hand, and Germany, Austro-Hungary, Bulgaria and Turkey, on the other. Romania was compelled to give away Dobrudja, to accept border adjustments in the Carpathians and to conclude unfavourable economic agreements.

International reactions

March 26^th - 28^th - The Rome Congress of Austro-Hungarian Empire nationalities, voting a motion in favour of recognising the right of each nation to form an independent national state or to unite with its own national state in case it existed.
Aug. 24^th Paris - The founding of the National Council of Romanian Unity, led by Take Ionescu (president), Vasile Lucaciu, Octavian Goga, Dr. Constantin Angelescu and Ioan Th. Florescu. The Council was recognised on the 29^th of September by the French government, on the 23^rd of October by the USA, on the 29^th of October by the British government and on the 9^th of November by the Italian one, as representing the interests of the Romanian people.
Sept. 2^nd - The New York Congress of the Romanians, Czechs, Slovaks, Poles, Serbs, Croats and Carpatho-Russians voted a motion demanding the dissolution of Austro-Hungarian Monarchy and the release of all peoples.

The Entente Offensive

Sept. 12^th - The Balkans allied armies broke through the Bulgarian Dobropolje front and advanced towards Sofia.
Sept. 16^th - the Salonik signing of the Bulgarian capitulation document.
Oct. 4^th - Germany, and then, Austro-Hungary, propose peace to the Allied Powers.

Sept. 29^th - The Executive Committee of the Romanian National Party, gathered at Oradea adopted unanimously a declaration drawn up by Vasile Goldis, demanding the recognition of this organisation as provisional leading body of Transylvania. An "Action Committee" was founded, with the headquarters at Arad, presided by Vasile Goldis.
Oct. 3^rd - The Manifesto of Emperor Charles the 1^st of Habsburg - To my faithful peoples, regarding the reorganising of Austro-Hungarian Monarchy into a Federation of six independent states (Austrian, Hungarian, Czech, Yugoslav, Polish and Ukrainian).
Oct. 3^rd - The Declaration of the "Body of Transylvania and Bukovina Volunteers" answering the manifesto of Charles the 1^st of Habsburg, and proclaiming the unification of their territories with the Romanian Kingdom.

The Entente's victory, that had begun to become clear by 1918 in the West, influenced also the Balkans front. Sarrail's army at Salonik finally advanced and broke through the Bulgarian lines. Marghiloman's government resigned on the 24^th of October / 6^th of November 1918. It was followed by general Coanda's government, that called immediately for general conscription and, on the 28^th of October / 10^th of November, Romania re-entered the war. A war that the following day ended by the armistice signed at Compiegne. It ended in western Europe, not in the eastern one, where, after the armistice, at Belgrade, on the 31^st of October / 13^th of November 1918, the military deeds would go on intermittently in Hungary. The military defeat entailed the dissolution of the central empires. The first one to crash down was, as expected, the Austro-Hungarian one. On the 18^th of October Emperor Charles (Franz Joseph had died in 1916) announced by a manifesto the transformation of the monarchy into a federal state. It was clearly much too late. The empire could no longer be saved, but the winners' diplomacy (especially that of Great Britain). But the peoples of the empire acted before the diplomats and decided their own fate. The Romanians as well on the 12^th of October, the Romanian National Party of Transylvania adopted the Declaration of self-determination, drawn up by Vasile Goldis in accordance with the national right of each nation to be its own master". Six days later, this Declaration was read in the Budapest Parliament by Alexandru Vaida Voevod, while in Vienna Iuliu Maniu concentrated 70,000 Transylvanian soldiers of the Austro-Hungarian army, with which he heads towards Transylvania. The Central Romanian National Council, founded on the 3^rd of November 1918, of the representatives of the Romanian National Party and the Democratic Social Party, overtook Transylvania's control, profiting also by the quick disintegration of the Hungarian administrative system.

Meanwhile, similar deeds took place in Bukovina, where on the 27^th of October a Romanian National Council was created, led by Iancu Flondor, who expressed Bukovina's desire to unite with Romania, actually proclaimed the unification, unconditionally, and with great enthusiasm at Cernauti, on the 28^th of November 1918. Karolyi Mihaly's government formed on the 31^st of October at Budapest, having as minister for nationalities the democrat Jaszi Oszkar, tried to negotiate with the Central Romanian National Council. The negotiations took place at Arad, between the 13^th and 15^th of November, but failed. At the same time the Hungarian government signed on the 13^th of November the Belgrade armistice with General Franchet d'Esperey, chief of the Orient army. An arbitrary borderline between Hungary and Transylvania was designed, leaving under Budapest's authorities towns like Satu Mare, Oradea, Beius, Arad and historical regions like the Banat (under Serbian administration), Crisana, Maramures. That put the Romanians on their guard. The National Council decided to convoke, on the 18^th of November / 1^st of December, at Alba-Iulia, a national Assembly of the Romanians in Transylvania and Hungary. This Assembly was going to include 600 elected deputies on the basis of suffrage universal and 628 representatives of cultural organisations and societies. All the Romanians in Transylvania, Crisana and Maramures cast their votes. In an atmosphere of great popular enthusiasm for 12 days were elected 5 representatives for each constituency, within the 1910 framework. The electors' claims were: unification with Romania, agrarian reform, and suffrage universal. The 1,228 deputies gathered in the Alba-Iulia Casino hall, while in town about 100,000 people (according to testimonies of the time) were waiting for their decisions. All the social categories and both churches were represented. Also representatives of all Romanian historical regions participated.

On the 18^th of November / 1^st of December 1918, the deputies unanimously decided the unification of Transylvania, the Banat, Crisana and Maramures with Romania, keeping at the same time a local autonomy, in accordance with democratic rules, including the equalities of nationalities and religions. At Alba-Iulia, as formerly at Cernauti, on the 25^th of November actually a plebiscite of all Romanians in Austro-Hungarian Monarchy took place. Also at Alba-Iulia, on the occasion of the Assembly, the Great Romanian National Council was formed of 200 elected members and 50 co-opted members. The following day, this Council named a provisional government, the Ruling Council of Transylvania, led by Iuliu Maniu. The Council sent a delegation to Bucharest, led by the Caransebes bishop, Miron Cristea (the future patriarch of Romania), who, on the 1^st/14^th of December, submitted the Alba-Iulia Declaration to King Ferdinand the 1^st. On the 11^th/24^th of December, King Ferdinand promulgated the decree of union sanctioning (including Bukovina and Bessarabia). The protests of Karolyi government at Budapest were futile.

After Ion Bulei, "Short History of the Romanians", Meronia Publishing House, Bucharest, 1996

For the inter-war period the only complete census of Romania's population was made in 1930, while the rest of the statistical references are only approximate. According to it, the country's population was of 18,052,896 people, 2,5 million more than in 1920. From the point of view of the ethnic stock, the Romanians represented the majority of the population, both before world war one and after its end, making up about 92% of the Old Kingdom and about 70% of the entire population of the united Romania, in 1920. In war died about 335,000 soldiers, who together with the civilian population killed during the battles, represented one tenth of Romania's population. The 8,5 million inhabitants joining the population of the Old Kingdom after the Great Unification compensated the war casualties. Romania's population counted in 1919, 16,250,000 million inhabitants, of which, 30% were not Romanian ethnics.

Hungarians 19,3%
Jews 5,3%
Ukrainians 4,7%
Germans 4,3%

In comparison with the period before the war, the number of the Romanians living outside the borders of the Romanian state decreased significantly: 250,000 in the USA, 230,000 in Yugoslavia, 60,000 in Bulgaria, 24,000 in Hungary. The national minorities lived mostly in the historical provinces returned to the fatherland:

Hungarians: 29% of Transylvania's population and 23% of that of Crisana and Maramures;
Germans: 24% of Banat's inhabitants and 8% of those of Transylvania;
Jews: 30% of Bukovina's urban population, 27% of Bessarabia's and 23% of Moldavia's.

After 1918 there were also emigrations abroad, however insignificant:

200,000 Hungarians from Transylvania to Hungary;
42,000 Turks from Dobrudja to Turkey;
67,646 emigrants left for the USA, between 1921 and 1930, most of them Jews.

Romania received immigrants as follows:

22,000 Jews from the USSR passed between 1918 and 1921 to Bessarabia;
in the 20's about 20,000 Romanians, who had immigrated to the USA before the war, returned to Transylvania and Bukovina.

Most of Romania's population lived in the countryside. Thus, in 1920 it represented 77% of the entire population.

According to Keith Hitchins, "Romania, 1866-1947", Humanitas Publishing House, Bucharest, 1996, chapter 8, "Society and Economy".