Ion I. C. Brătianu's political activities after World War I, including part of his third and fourth term, saw the unification of the Old Romanian Kingdom with Transylvania, Bukovina and Bessarabia (see: Greater Romania).

Born at Florica, his father's estate in Ștefănești, Argeș County, he completed his secondary education at the Saint Sava National College in Bucharest (1882).

In 1913, he convinced his party to accept a moderate version of land reform, as well as the creation of a single electoral college - a measure which would have given more accurate representation to the peasant majority.

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.

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.

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.

The spectre of socialist agitation, which had led to incidents such as a major strike action in Bucharest in December 1918, brought about the fall of the Constantin Coandă cabinet, and Brătianu again occupied the position.

At the same time, the People's Party, a new and strong populist movement under General Averescu, had begun a campaign for both an urgent land reform and for bringing about the prosecution of PNL politicians as agents of the economic hardships.

By that moment, the general was thought by the PNL to be a convenient agent of its own policies, but Averescu's negotiations for a return of the disinherited Prince Carol after his father's imminent death made Brătianu switch his support to a broad coalition government under Barbu Ştirbey.