garrison. The following year, Antonescu was promoted to Lieutenant, and, between 1911 and 1913, he attended the Advanced War School, receiving the rank of Captain upon graduation. In 1913, during the Second Balkan War against Bulgaria, Antonescu served as a staff officer in the First Cavalry Division in Dobruja. World War I After 1916, when Romania entered World War I on the Allied side, Ion Antonescu acted as chief of staff for General Constantin Prezan. When enemy troops crossed the mountains from Transylvania into Wallachia, Antonescu was ordered to design a defense plan for Bucharest. The Romanian royal court, army, and administration were subsequently forced to retreat into Moldavia. Antonescu took part in an important decision involving defensive efforts, an unusual promotion which probably stoked his ambitions. In December, as Prezan became the Chief of the General Staff, Antonescu, who was by now a major, was named the head of operations, being involved in the defence of Moldavia. He contributed to the tactics used during the Battle of Mărășești (July–August 1917), when Romanians under General Eremia Grigorescu managed to stop the advance of German forces under the command of Field Marshal August von Mackensen. Being described as "a talented if prickly individual", Antonescu lived in Prezan's proximity for the remainder of the war and influenced his decisions. Such was the influence of Antonescu on General Prezan that General Alexandru Averescu used the formula "Prezan (Antonescu)" in his memoirs to denote Prezan's plans and actions. That autumn, Romania's main ally, the Russian Provisional Government, left the conflict. Its successor, Bolshevik Russia, made peace with the Central Powers, leaving Romania the only enemy of the Central Powers on the Eastern Front. In these conditions, the Romanian government made its own peace treaty with the Central Powers. Romania broke the treaty later in the year, on the grounds that King Ferdinand I had not signed it. During the interval, Antonescu, who viewed the separate peace as "the most rational solution," was assigned command over a cavalry regiment. The renewed offensive played a part in ensuring the union of Transylvania with Romania. After the war, Antonescu's merits as an operations officer were noticed by, among others, politician Ion G. Duca, who wrote that "his [Antonescu's] intelligence, skill and activity, brought credit on himself and invaluable service to the country." Another event occurring late in the war is also credited with having played a major