Following the invasion of Belgium and France in August 1914, the atrocities committed by German imperial troops earned them a reputation as "barbarians" that ultimately proved hugely counter-productive.
The Germans justified the massacre of thousands of civilians and the destruction of cultural treasures by invoking the threat of snipers among the population, a claim that was strongly disputed by historians after the war.
The violence provided ample material for Allied propagandists. Journalists from neutral countries, like those of the New York World or the Netherlands' Telegraaf, catalogued abuses during the advance of the Kaiser's troops -- including summary executions, mass rapes, brutal seizure of property and the systematic destruction of homes.
According to Irish historian John Horne, German forces executed a total of 6,500 Belgian civilians. During the first three months of their occupation of the French region of Lorraine alone, they deported 25,000 people and burned down nearly 20,000 buildings.
In the space of just two days on August 22 and 23, more than 1,200 civilians, including women and children, were executed at Ardenne, Dinant and Tamines, three villages in southern Belgium, according to witnesses called by a Belgian commission of enquiry after the war.
At Senlis, taken as the Germans advanced on Paris, the mayor was shot in the head before the soldiers set fire to the historic French town.
The "new Huns", as they came to be known, burned down such treasures as the Ypres Cloth Hall and Leuven library in Belgium, and bombed cathedrals at Reims, Soissons and Senlis.
German intellectuals rallied to the defence of their military. In October 1914, a group of 93 intellectuals signed a declaration -- which they described as a "call to all civilised nations" -- describing the attacks on civilians as "legitimate self-defence" against a population that has "ceaselessly and treacherously fired on our troops".
Once the front had stabilised, the Belgian population, along with those of 10 departments in northeast France, lived through four years of harsh occupation.
Forced labour and mass deportations were common. An estimated 120,000 Belgian workers were deported to factories in Germany and occupied France, where some 2,600 would die. Occupied civilians also bore the brunt of the acute food shortages caused by the Allied naval blockade.
Around 100,000 civilians were detained during the war in concentration camps -- a relatively new concept that was first used by the British in Africa at the turn of the century, and would later be put to infamous use on an industrial scale by the Nazis.
- Hugely counter-productive -
During their tactical retreat to the Hindenburg Line in March-April 1917, the Germans destroyed everything in their path for dozens of miles in a bid to obstruct their Allied pursuers. They forcibly evacuated 160,000 French civilians in the process, with orders that "the enemy should find only a desert upon his arrival".
Right up to the armistice in November 1918, the Germans continued this scorched-earth policy, systematically destroying French and Belgian factories, flooding mine shafts, poisoning wells and hacking down fruit trees.
The abuses of the German army proved hugely counter-productive. Along with their use of poison gas on the battlefield and their sinking of neutral ships -- all in contravention of the Hague Conventions on the Laws of War signed in 1907 -- the reports shocked public opinion in the United States, hastening its entry into the war.
These actions would also be invoked by Belgium and France to justify huge demands for reparations -- 132 billion gold marks -- from Germany after the war, as well as their occupation of the Ruhr valley, Germany's main industrial base, in 1925-26.
War crimes would also become an acute source of rancour between the opposing sides. Germany was furious over charges against 2,000 of its soldiers for war crimes under the Treaty of Versailles, while the Allies were greatly frustrated when only a handful were ever brought to trial, many of them acquitted or given symbolic sentences.