The son of a postal official, Meissner studied law in Strasbourg from 1898 to 1903, where he also became a member of the Strassburg Student Youth Fraternity (Burschenschaft) Germania. Later he also studied in Berlin and earned his Doctor of Laws in 1908, at the age of 28, in Erlangen, Bavaria. Afterwards, he became a bureaucrat for the national railroad, the Reichsbahn, in Strasbourg. Between 1915 and 1917 he participated in the First World War in an infantry regiment. Up to 1919 he was more active behind the front, first in Bucharest, Romania, then in Kiev, and finally as a German business agent for the Ukrainian government.