Eduard von Liebert joined the 58th (3rd Posen) Infantry Regiment of the Prussian Army as an ensign at a very early age. He saw action in the Battle of Nachod in 1866 and was promoted to lieutenant on August 6th. Four years later, in 1870, he took part in the Franco-Prussian War, and was lightly wounded near Wörth, but was able to rejoin the fighting around Paris. For this, he received the Iron Cross. He attended the Prussian Staff College () afterwards, graduating from there when 26 years old, in 1872. Afterwards, he was an instructor at the Military School in Hanover. While there, in 1878, he was one of he twelve citizens who formed the "Provisional Committee for the Foundation of a Geographical Society in Hanover. He was promoted to captain in 1880 and joined the general staff in the military college at Metz where he taught military strategy. He became a major in 1886.