Mihail Sadoveanu

Context: Sadoveanu returned to his administrative job in 1907, the year of the Peasants' Revolt. Kept in office by the National Liberal cabinet of Ion I. C. Bratianu, he served under the reform-minded Education Minister Spiru Haret. Inspired by the bloody outcome of the Revolt, as well as by Haret's moves to educate the peasantry, Sadoveanu reportedly drew suspicion from the Police when he published self-help guides aimed at industrious ploughmen, a brand of social activism which even resulted in a formal inquiry.  Mihail Sadoveanu became a professional writer in 1908-1909, after joining the Romanian Writers' Society, created in the previous year by poets Cincinat Pavelescu and Dimitrie Anghel, and becoming its President in September of that year. The same year, he, Iosif, and Anghel, together with author Emil Garleanu, set up Cumpana, a monthly directed against both Ovid Densusianu's eclecticism and the Junimist school (the magazine was no longer in print by 1910). At the time, he became a noted presence among the group of intellectuals meeting in Bucharest's Kubler Coffeehouse.  In 1910, he was also appointed head of the National Theater Iasi, a position which he filled until 1919. That year, he translated from the French one of Hippolyte Taine's studies on the genesis of artworks. He resigned his office within the Writers' Society in November 1911, being replaced by Garleanu, but continued to partake in its administration as a member of its leadership committee and a censor. He was a leading presence at Minerva newspaper, alongside Anghel and critic Dumitru Karnabatt, and also published in the Transylvanian traditionalist journal, Luceafarul.  Sadoveanu was again called under arms during the Second Balkan War of 1913, when Romania confronted Bulgaria. Having reached the rank of Lieutenant, he was stationed in Falticeni with the 15th Infantry Regiment, after which he spent a short period on the front. He returned to literary life. Becoming good friends with poet and humorist George Topirceanu, he accompanied him and other writers on cultural tours during 1914 and 1915. The series of writings he published at the time includes the 1915 Neamul Soimarestilor.  In 1916-1917, as Romania entered World War I and was invaded by the Central Powers, Sadoveanu stayed in Moldavia, the only part of Romania's territory still under the state's authority (see Romanian Campaign). The writer oscillated between the Germanophilia of his Viata Romaneasca friends, the stated belief that war was misery and the welcoming of Romania's commitment to the Entente Powers. At the time, he was reelected President of the Writers' Society, a provisional mandate which ended in 1918, when Romania signed the peace with the Central Powers, and, as Army reservist, edited the Entente's regional propaganda outlet, Romania. He was joined by Topirceanu, who had just been released from a POW camp in Bulgaria, and with whom he founded the magazine Insemnari Literare. Sadoveanu subsequently settled in the Iasi neighborhood of Copou, purchasing and redecorating the villa known locally as Casa cu turn ("The House with a Tower"). In the 19th century, it had been the residence of politician Mihail Kogalniceanu, and, during the war, hosted composer George Enescu. During that period, he collaborated with leftist intellectual Vasile Mortun and, together with him and Arthur Gorovei, founded and edited the magazine Ravasul Poporului. CANNOTANSWER

Question: what was Mihail Sadoveanu's greatest accomplishment named in the article?
Answer: Mihail Sadoveanu became a professional writer in 1908-1909, after joining the Romanian Writers' Society,