Schrecklichkeit Schrecklichkeit ( German " terror " or " frightfulness " ) is a word used by English speakers to describe an assumed military policy of the German Army towards civilians in World War I . Under the traditional " laws of war " in Europe , military activity was to be confined to the regular , uniformed armies of each side . Civilians were to take no part in fighting , neither attacking or being attacked . Thus , when the uniformed army troops in a nation or region were all defeated , resistance was supposed to end . In practice , informal resistance by " partisans " , " guerrillas " , or " " francs - tireurs " " often continued after the " regular " troops had given up or withdrawn . These fighters , never officially enrolled in an army , and not wearing uniforms to identify them as combatants , attacked occupying troops by ambushes , surprises , and sniping . Conducting such operations out of uniform was considered perfidy , and those involved could be executed . Occupying armies sometimes responded to such attacks by reprisals against the local population : execution of local inhabitants , whether known to be guerrilas or not , or destruction ( usually by burning ) of homes and other structures . German army doctrine in force at the time called for such reprisals to be performed immediately and severely in any case of civilian resistance . It was argued that such " schrecklichkeit " would end resistance quickly with relatively little bloodshed , whereas restraint would encourage resistance , leading to greater destruction and death . When Germany invaded Belgium in 1914 , the German high command expected to sweep through the country with negligible opposition . The German army was many times larger and stronger than the Belgian army , and the Germans therefore thought that any resistance by Belgium would be futile . German leaders had even suggested to the Belgian government that in the event of war , the Belgians should just line up along the roads and watch the Germans march through . Belgium ' s refusal to accept these German presumptions and its resistance to the German advance came as a surprise , and disrupted the German timetable for advancing into France . This frustration was communicated to the German troops in Belgium . Anything which delayed the German advance was to be crushed mercilessly . The Belgians were viewed as irrational and even treacherous for their opposition . This led to exaggerated suspicions among German commanders of Belgian civilian resistance . It is possible that some Belgian civilians engaged in resistance , though none is documented . It is certain that on several occasions , German commanders declared ( probably in unconscious error ) that such acts had occurred when they had not . The Germans responded to these perceived acts of resistance with harsh measures . In several villages and towns , hundreds of civilians were executed . Many buildings were put to the torch . Priests thought guilty of encouraging the resistance were killed . Violence by German soldiers against Belgians , such as rape , was ignored or not seriously punished . The Belgian city of Leuven was largely destroyed . One German officer later wrote about the town , " We shall wipe it out . . . Not one stone will stand upon another . We will teach them to respect Germany . For generations people will come here and see what we have done " . These actions , taken in a period of near - panic as the German forces desperately tried to carry out their flanking march before Allied forces could respond , proved to be a propaganda disaster for Germany . The reports of them caused a wave of indignation which aided the Allied cause . Analysis . The German argument for many years was that the actions in Belgium were the result of civilian resistance . The Belgian government was to blame for this " illegal warfare . " Echoes of this can be found as late as the 1990s in such works as " Deutsche Geschichte " of Thomas Nipperdey and in the 1996 edition of the " Brockhaus Enzyklopädie " . John Horne and Alan Kramer in " German Atrocities 1914 : A History of Denial " contest this . Based on several sources , they contend that the German Army faced no irregular forces in Belgium and France during the first two and a half months of World War I , but believed it did due to erroneous reports of civilian resistance and as a result responded inappropriately and with excessive force .