He was born in Călărași, the third of 14 children of Petre Bănescu, a lawyer, and his wife Ecaterina, née Drăgulănescu.
[1][2] He pursued his studies at the Faculty of Letters and Philosophy of the University of Bucharest, graduating in 1901, after which he taught at the Carol I High School in Craiova and the I.C.
From 1910 to 1912 Bănescu attended the University of Munich, where he obtained his Ph.D. degree in Byzantine studies in July 1914,[1][2] with thesis Die Entwicklung des griechischen Futurums von der frühbyzantinischen Zeit bis zur Gegenwart written under the direction of August Heisenberg.
[4] From 1912 to 1914 he was director of the Mănăstirea Dealu Military Lyceum [ ro] in Târgoviște and in the summer of 1913 he participated in the Second Balkan War as officer in the reserves.
When Romania entered World War I in 1916 on the side of the Allies, he joined the Romanian Land Forces as a lieutenant.