Armed conflict Perpetrator
Incident Type of crime Persons responsible Notes
World War I German Empire (Imperial Germany)
Rape of Belgium War crimes Leipzig war crimes trials In defiance of the 1907 Hague Convention on Land Warfare, the German occupiers engaged in mass atrocities against the civilian population of Belgium and looting and destruction of civilian property, in order to flush out the Belgian guerrilla fighters, or francs-tireurs, in the first two months of the war, after the German invasion of Belgium in August 1914.[39]
As Belgium was officially neutral after hostilities in Europe broke out and Germany invaded the country without explicit warning, this act was also in breach of the treaty of 1839 and the 1907 Hague Convention on Opening of Hostilities.[40]

World War I All major belligerents
Employment of poison gas Use of poisons as weapons No prosecutions Poison gas was introduced by Imperial Germany, and was subsequently used by all major belligerents in the war, in violation of the 1899 Hague Declaration Concerning Asphyxiating Gases and the 1907 Hague Convention on Land Warfare.[41][42]
World War I Ottoman Empire
Armenian genocide[43][44][45][46][47][48] War crimes, crimes against humanity, crime of genocide (extermination of Armenians in Western Armenia) The Turkish Courts-Martial of 1919–20 as well as the incomplete Malta Tribunals were trials of some of the perpetrators.
Several key perpetrators of the genocide were assassinated by Armenian vigilantes as part of Operation Nemesis.

The Young Turk regime ordered the wholesale extermination of Armenians living within Western Armenia. This was carried out by certain elements of their military forces, who either massacred Armenians outright, or deported them to Syria and then massacred them. Over 1.5 million Armenians perished.[citation needed]
The Republic of Turkey, the successor state of the Ottoman Empire, does not accept the word genocide as an accurate description of the events surrounding this matter.[49]

Assyrian genocide War crimes, crimes against humanity, genocide, ethnic cleansing Several key perpetrators of the genocide were assassinated by Armenian vigilantes as part of Operation Nemesis Mass killing of Assyrian civilians by the Ottoman Empire's forces resulting in the deaths of hundreds of thousands. Turkey does not call the event genocide.
Greek genocide War crimes, crimes against humanity, genocide, ethnic cleansing The Turkish Courts-Martial of 1919–20 as well as the incomplete Malta Tribunals were trials of some of the perpetrators.
Several key perpetrators of the genocide were assassinated by Armenian vigilantes as part of Operation Nemesis.

Violent ethnic cleansing campaign against Greeks in Anatolia resulting in the deaths of hundreds of thousands. Turkey does not call the event genocide.
World War I United Kingdom
Baralong Incidents War crimes (murder of shipwreck survivors) No prosecutions On 19 August 1915, a German submarine, U-27, while preparing to sink the British freighter Nicosian, which was loaded with war supplies, after the crew had boarded the lifeboats, was sunk by the British Q-ship HMS Baralong. Afterwards, Lieutenant Godfrey Herbert ordered his Baralong crew to kill the survivors of the German submarine while still at sea, including those who were summarily executed after boarding the Nicosian. The massacre was reported to a newspaper by American citizens who were also on board the Nicosian.[50] Another attack occurred on 24 September a month later when Baralong destroyed U-41, which was in the process of sinking the cargo ship Urbino. According to U41's commander Karl Goetz, the British vessel was flying the American flag even after opening fire on the submarine, and the lifeboat carrying the German survivors was rammed and sunk by the British Q-ship.[51]
World War I Russian Empire
Urkun War crimes, crimes against humanity, genocide No prosecutions
Urkun was not covered by Soviet textbooks, and monographs on the subject were removed from Soviet printing houses. As the Soviet Union was disintegrating in 1991, interest in Urkun grew. Some survivors have begun to label the events a "massacre" or "genocide".[52] In August 2016, a public commission in Kyrgyzstan concluded that the 1916 mass crackdown was labelled as "genocide".[53] Arnold Toynbee alleges 500,000 Central Asian Turks perished under the Russian Empire, though he admits this is speculative.[54] Rudolph Rummel citing Toynbee states 500,000 perished within the revolt.[55][unreliable source?] Kyrgyz sources put the death toll between 100,000 and 270,000. Russian sources put the figure at 3,000.[56] Kyrgyz historian Shayyrkul Batyrbaeva puts the death toll at 40,000, based on population tallies.[citation needed]

Deportation of Volhynia Germans War crimes, crimes against humanity Although Germans were permitted to return and attempt to reclaim their land, it is estimated that only one-half of their number did so. Many found their houses destroyed and their farms occupied by strangers.[57] Grand Duke Nicholas (who was still commander-in-chief of the Western forces), after suffering serious defeats at the hands of the German army, decided to implement the decrees for the German Russians living under his army's control, principally in the Volhynia province. The lands were to be expropriated, and the owners deported to Siberia. The land was to be given to Russian war veterans once the war was over. In July 1915, without prior warning, 150,000 German settlers from Volhynia were arrested and shipped to internal exile in Siberia and Central Asia. (Some sources indicate that the number of deportees reached 200,000.) Ukrainian peasants took over their lands. The mortality rate from these deportations is estimated to have been 63,000 to 100,000, that is from 30% to 50%, but exact figures are impossible to determine.[citation needed]
World War I Kingdom of Bulgaria
Surdulica massacre Summary executions No prosecutions The Surdulica massacre was the mass murder of Serbian men by Bulgarian occupational authorities in the southern Serbian town of Surdulica in 1916 and early 1917, during World War I. Members of the Serbian intelligentsia in the region, mostly functionaries, teachers, priests and former soldiers, were detained by Bulgarian forces—ostensibly so that they could be deported to the Bulgarian capital, Sofia—before being taken into the forests around Surdulica and killed. An estimated 2,000–3,000 Serbian men were executed by the Bulgarians in the town and its surroundings. Witnesses to the massacre were interviewed by American writer William A. Drayton in December 1918 and January 1919.[58]
World War I
Štip massacre Summary executions No prosecutions The Štip massacre was the mass murder of Serbian soldiers by the IMRO paramilitaries in the village of Ljuboten, Štip on 15 October 1915, during World War I. Sick and wounded Serbian soldiers, recuperating at the Štip town hospital, were detained by Bulgarian IMRO militants before being taken into the vicinity of Ljuboten and killed. An estimated 118–120 Serbian soldiers were executed in the massacre.[59]