Major Speller reorganized Luxembourg's troops on 24 February 1939. He still served as the force's commander during the German invasion of Luxembourg on 10 May 1940. Most of the soldiers did not partake in the fighting, as only those who volunteered for guard duty were stationed along the border. The rest remained in their barracks, leaving the defence of the country to the Grand Ducal Gendarmerie. Total casualties amounted to six gendarmes and one soldier wounded. Twenty-two soldiers (six officers and 16 non-commissioned officers) and 54 gendarmes were captured.