The outbreak of the world conflict in
1914 brought a major polemic in Romanian society. The Conservatives oscillated between a
neutral stance and participation alongside the
Central Powers (to which Romania had committed itself); instead, the PNL called for an alignment with the
Entente Forces. Despite the fact that Brătianu was again Prime Minister from
January 16, 1914 to
February 9, 1918, his policies in this respect were procrastinated. Initially, a decision on the matter was blocked by King Carol, until his death in October 1914. Afterwards, with the ascension of
Ferdinand I (who was to remain a political ally of Brătianu for the rest of his life), the government started secret negotiations with the Entente, meant to condition Romania's participation with the granting of
Austro-Hungarian lands with a majority
Romanian population. In August
1916, Romania declared war on Austria-Hungary.
Minor advances into Transylvania were met with a Central Powers counter-offensive that swept through
Oltenia and
Wallachia, occupied
Bucharest, and forced all governmental structures to take refuge in
Iaşi. While
Moldavia remained the only region under Romanian administration and the country increased its reliance on
Imperial Russia - and then on the
Russian Provisional Government, the Romanian Army was able to block further Central Powers' offensives in the battles of
Mărăşeşti, Mărăşti, and
Oituz. This situation was ended by the
October Revolution in Russia and the
Treaty of Brest-Litovsk between the
Bolshevik government and the Central Powers: Romania saw itself without reinforcements, agreed to an
armistice, and then signed the
Treaty of Bucharest in May 1918.
In the meantime, Brătianu's had been replaced with the crisis government of General
Alexandru Averescu, and this was soon followed by
Alexandru Marghiloman's (chosen to negotiate the peace, as the
German Empire was thought to be friendly towards Marghiloman). Nonetheless, Romania never did
ratify the signed treaty, and
denounced it in October 1918, immediately re-entering the conflict on the Entente's side. In November, the
Compiègne armistice with
Germany removed all legal value of the Bucharest Treaty.