During the war, he participated in several battles, notably Ypres (1915), the Somme (1916) and Verdun, earning the Iron Cross second and first class.

After the war and his dismissal from the greatly reduced army, Schlageter described himself as a student of political sciences, but he studied the subject at the most for one year.

After the Landwehr was defeated in the Battle of Cēsis, he joined the German Legion of the West Russian Volunteer Army led by Pavel Bermondt-Avalov.

In December 1919, after Avalov's forces were defeated by the Latvian Army and after a short time in Lithuania, Schlageter returned to Germany.

[5] During the Third Silesian Uprising of 1921, Schlageter became infamous for persecuting local people and for terrorist actions against both Poles and Germans whom he and his group perceived as opposing his cause.

[7] Following the French occupation of the Ruhr in 1923, Schlageter led a group of nationalists in sabotage operations against the occupying force.

On May 8, Schlageter had written to his parents: "from 1914 until today I have sacrificed my whole strength to work for my German homeland, from love and pure loyalty.

The German Communist Party sought to debunk the emerging mythology of Schlageter by circulating a speech by Karl Radek portraying him as an honourable but misguided figure.

[13] In June 1933, Nazis from the Passau region gathered at the Dreisessel Mountain in the Bavaria Forest to dedicate a Schlageter Memorial.

The line "when I hear the word culture, I reach for my gun", often misattributed to Nazi leaders, derives from this play.

[19] Schlageter also featured as a prominent character in British author Geoffrey Moss's 1933 novel I Face the Stars, about the rise of Nazism.

After the war, the main Schlageter memorial was destroyed by occupying Allied forces as part of the denazification process.