After the war, the perceived affronts of the Treaty of Versailles kept some of these nationalistic feelings running high, especially in Lenard, who had already complained about England in a small pamphlet at the beginning of the war. When, on 26 January 1920, the former naval cadet Oltwig von Hirschfeld tried to assassinate German Finance minister Matthias Erzberger, Lenard sent Hirschfeld a telegram of congratulation. After the 1922 assassination of politician Walther Rathenau, the government ordered flags flown at half mast on the day of his funeral, but Lenard ignored the order at his institute in Heidelberg. Socialist students organized a demonstration against Lenard, who was taken into protective custody by state prosecutor Hugo Marx.