Schrecklichkeit, or terror--frightfulness--was an instrument of the German invasion of Belgium and France, and it was intended to disarm or destroy any civilian resistance to the advance of the German armies. Out of the initial haste and rush of the invading forces were born the atrocities against civilians that in turn spawned many of the initial (and enduring) images, in the Allied press, of the invading forces. Note these passages from Winter and Baggett's The Great War and the Shaping of the 20th Century (1996):
"Since speed was of the essence, no civilian harassment or irregular warfare would be tolerated by the Germans. They used heavy artillery, including the siege gun 'Big Bertha' . . . on the town centre of the city of Louvain; they shot hostages; burnt villages, and when women were raped by German soldiers, their commanders did little about it" (p. 67).
"The old traditions [of war in Europe] . . . called for the end of a country's hostilities when its army was beaten on the battlefield. Belgium fought differently--and the German response was savage. 'Our advance in Belgium,' wrote Moltke on 5 August, 'is certainly brutal, but we are fighting for our lives and all who get in the way must take the consequences.' On that day a number of Belgian priests had been executed for encouraging resistance to the invasion. But the Belgians needed little encouragement from their priests, as snipers shot at German soldiers laden with 25 kg packs on their backs through fields and villages. The invading forces and their commanders responded with an iron fist, burning homes, rounding up villagers--men, women, and in some cases children--and shooting groups of them: six at Warsage, fifty at Seilles, nearly four hundred at Tamines and over six hundred at Dinant. The medieval town of Louvain was heavily shelled and its university's library, a treasure-house of ancient manuscripts, was torched. 'We shall wipe it out,' declared one German officer. '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' "(pp. 65-6).
In this way, the fresh German army, heady with its cake-walk through ineptly defended Belgium, committed initial abuses that were to haunt it ever after. The events in Belgium were terrible, and Germany was the over-whelming victor, but Moltke's 'brutal advance' actually represented a disaster for Germany, in regard to propaganda and the Allied waging of the newspaper war.