Buchner married Lotte Stahl in 1900. At the outbreak of the First World War he volunteered and rose to the rank of Major commanding a munition-transport unit on the western and then eastern front. In March 1916 he returned the University of Wurzburg. In April 1917 he volunteered again. On 11 August 1917, while stationed at Focșani, Romania, he was hit by a shell fragment and died two days later. He died in the Battle of Mărășești and is buried in the cemetery of German soldiers from Focșani, Romania.