During the Second World War, resistance movements that bore any resemblance to irregular warfare were frequently dealt with by the German occupying forces under the auspices of anti-partisan warfare. In many cases, the Nazis euphemistically used the term "anti-partisan operations" to obfuscate ethnic cleansing and ideological warfare operations against perceived enemies; this included Jews, Communist officials (so-called Jewish Bolsheviks), Red Army stragglers, and others. This was especially the case on the Eastern Front, where anti-partisan operations often resulted in the massacres of innocent civilians. While the worst atrocities in terms of scale occurred in the Eastern theater of the war, the Nazis employed "anti-partisan" tactics in Western Europe as well.

Historian Alex J. Kay estimates that around one million civilians may have died as a result of German anti-partisan warfare—excluding actual partisans—among the 13 to 14 million people murdered by the Nazis during World War II.

A. Dirk Moses notes that the German security warfare was an extreme version of strategies and tactics pursued by other colonial powers against anti-colonial resistance. "All resistance was regarded as illegitimate, and civilians were targeted preemptively and often collectively to forestall future resistance", while the laws of war were suspended on the basis that the enemy was barbarian.

Origins and military doctrine

The forms of resistance varied depending on place and time, and so did the Germans' countermeasures.Daniel Marston, Carter Malkasian, Counterinsurgency in Modern Warfare, Osprey Publishing, 2008, , Google Print, p.74-83 Both the scale of resistance and the severity of German reprisals were much more limited in the West than in the East.Daniel Marston, Carter Malkasian, Counterinsurgency in Modern Warfare, Osprey Publishing, 2008, , Google Print, p.83-90 While Germans were much more likely to treat the entire local populace as enemies in the East, they were much less ideologically driven in the West, where, for example, women and children were only rarely killed by SS troops, but were a much more common target in the East. Some scholars have noted that in the East, the anti-partisan operations gave Germans a pretext for ideologically motivated ethnic cleansing.Daniel Marston, Carter Malkasian, Counterinsurgency in Modern Warfare, Osprey Publishing, 2008, , p.70-74

In the context of the German campaign against so-called "partisans" in the occupied territories, SS Chief Heinrich Himmler framed security operations as a struggle for the survival of the Reich. He cast local resistance not as legitimate military opposition but as a form of criminality threatening the German people, thereby justifying draconian measure. As he explained in December 1941:

The Germans concentrated on short-term victories against the partisans and were able, in some cases, to defeat the partisans militarily, but overall their atrocities against civilians in the East resulted in a continuous flow of volunteers joining the partisan ranks. The first resistance movements were created as early as late 1939 in occupied Poland (see the Separated Unit of the Polish Army). As the war progressed and the number of Nazi-occupied territories grew, so did the number and strength of resistance movements.

Throughout the war, regular formations of German army, auxiliary police formations (Ordnungspolizei) and their helpers (Schutzmannschaft or Hilfspolizei) participated in anti-partisan operations. The struggle of Germans versus the partisans can be described as a stalemate, eventually ended by the German military defeat in the regular war. After the war, brutal German tactics used against the partisans were one of the charges presented at the Nuremberg Trials (see legality of the Commando Order and Hostages Trial).

Operations by country and territory German-occupied Poland

The Polish resistance movement was formed soon after the German invasion of Poland in September 1939 and quickly grew in response to the brutal methods of the German occupation. Polish resistance had operatives in the urban areas, as well as in the forests (leśni). Throughout the war, the Polish resistance grew in numbers, and increased the scale of its operations, requiring the Germans to devote an increasing amount of resources (personnel, equipment and time) to deal with the partisan threat.

Polish partisans were particularly active in the Zamość region (see the Zamość Uprising). Sturmwind I and Sturmwind II ("Hurricane") in June 1944 were the largest German operations against the Polish leśni partisans, based on the "cauldron operations" Germans developed to deal with the Soviet partisans (see also battle of Osuchy). German losses in those operations amounted to about 1,300 fatalities and similar number of wounded; partisan losses were similar. Soon afterward, the Polish resistance launched a series of major operations against the Germans (Operation Tempest), of which the Warsaw Uprising was the best known. In Operation Tempest, Polish partisans challenged the Germans in a series of open battles for the control of vital strategic areas. The Germans were not prepared for the vast scale of the Polish operation, but had the advantage of numbers and better equipment; further, when the Polish partisans had to operate without the support of the advancing Red Army, they were significantly less effective. In areas where the Soviets cooperated with the Poles, the Germans were much less able to suppress the partisans, but where the Soviets did not advance to aid the Poles, as was the case with the Warsaw Uprising, the Germans were able to concentrate enough regular army and anti-partisan units to defeat the Polish insurgents.

The tactics and policies the Germans developed in Poland served as a template for similar operations against the Soviet partisans.Ben H. Shepherd, War in the wild East: the German Army and Soviet partisans, Harvard University Press, 2004 , Google Print, p.46, p.56

German-occupied areas of the Soviet Union

In early 1941 Germans set up special units – Wehrmacht Security Divisions – to deal with securing the rear and carrying out anti-partisan duties. These formations were also involved in the repression of civilians, including participation in The Holocaust by rounding up Jews.

The policies the Germans employed in the occupied Soviet territories were the extension of the brutal policies they had developed over the previous two years in occupied Poland. At first, the Germans tried to cow the local populace with violence. The policies of 1941 were aimed more at a potential threat than a real one, as the Soviet partisans were only just organizing in the aftermath of the German invasion. It was on the Eastern Front (including the Balkans) that there was the greatest German terror against the local populace. To a certain degree, it is hard to distinguish pure military anti-partisan operations from ethnic cleansing actions.

With the German failure to topple the Soviet Union in the first year of the war, the anti-partisan policy changed, switching from short-term to a more long-term view. Nazi propaganda and similar tactics were employed in order to influence the local populace and make them more friendly towards the Germans (and less towards the partisans). It was at this time that Germans started to support the creation of local auxiliary units to be used against the partisans. The anti-partisan operations also became more professional and better organized.

By late 1942, the "hearts and minds" policy had already weakened. Around 1942–1943, large-scale "encirclement operations" were employed, which involved the use of regular army units, detached from the frontline, against the partisans. Such operations often involved the destruction of villages that were seen as potentially supporting the partisans; that meant both the physical destruction of the buildings and the massacres of local inhabitants. These "encirclement operations" antagonized the local populace, contributing to the growth, not shrinking, of the Soviet partisans' ranks. Major "encirclement operations" included Operation München and Operation Bamberg (March–April 1942), Operation Hannover (May–June 1942), Operation Vogelsang (June–July 1942) and Operation Zigeunerbaron ("Gypsy Baron", May–June 1943).

In 1944, a new policy was introduced: the creation of , or fortified villages. This project, seen by Germans as one of the most successful German anti-partisan policies (and later imitated by other armies, for example, the French in Algeria or the United States in Vietnam), involved the creation of autonomous and well-armed villages, in collaboration with local Nazi sympathizers. The advance of the Red Army and liberation of the remaining Soviet territories from under the German occupation prevented the full implementation of this policy.

German-occupied Italy

Casualties in Italy among the Italian Resistance Movement include 35,828 partisans killed in action or executed, and 21,168 partisans mutilated or left disabled by their wounds.Giuseppe Fioravanzo, La Marina dall'8 settembre 1943 alla fine del conflitto, p. 433. Another 32,000 Italian partisans were killed abroad (in the Balkans and, to a lesser extent, in France). According to other estimates, the Italian resistance lost some 50,000 fighters throughout the conflict. Thousands to tens of thousands of Italian civilians were killed in reprisals by the German and Italian Fascist forces.

Armed resistance to the German occupation following the armistice between Italy and Allied armed forces at first included mainly the Italian regular forces, such as the Italian Armed Forces and the Carabinieri military police. Later, the Comitato di Liberazione Nazionale (Committee of National Liberation, or CLN), created by the Italian Communist Party, the Italian Socialist Party, the Partito d'Azione (a republican liberal socialist party), Democrazia Cristiana and other minor parties, took control of the movement.

In their attempts to suppress the Resistance, German and Italian Fascist forces (especially the SS, Gestapo, and paramilitary militias such as Xª MAS and Black Brigades) committed war crimes, including summary executions and systematic reprisals against the civilian population. Resistance captives and suspects, as well as random local Italian civilians, were often tortured and raped. Italian partisans, especially those in the mountainous and rural regions, relied heavily on the local populace for support and supplies. The Nazis tried to punish the populace and discourage civilian support for the Resistance by adopting a reprisal policy of killing 10 Italians for every German killed by the partisans. Those executed would usually come from the village near where a partisan attack against Nazis took place and sometimes included captive partisan fighters themselves.

Some of the most notorious mass atrocities included the Ardeatine massacre (335 Italian Jewish civilians and Italian political prisoners executed in a reprisal operation the day after the Via Rasella attack in Rome), the Sant'Anna di Stazzema massacre (about 560 random Italian villagers brutally killed in an anti-partisan operation in the central mountains), the Marzabotto massacre (about 770 Italian civilians killed in similar circumstances) and the Salussola massacre (20 Italian partisan murdered after being tortured). In all, an estimated 15,000 Italian civilians were deliberately killed, including many women and children.