General Helmuth Pannwitz and his Cossack body guard regiment.
During the Second World War, ethnic Cossacks fought on both sides of the conflict. Cossacks who had emigrated to the USA and the UK served with their military forces. Many Cossacks joined the Resistance. Though some Cossacks joined German armed forces, they did so usually to defect either to the western allies or to the Resistance, to liberate their co-patriots and family members from Nazi work and concentration camps.
The vast majority of the ethnic Cossacks fought against the Nazis in the ranks of the Red Army and of the Red Navy on all war theaters. Their service was crucial on the Southern theater of the Eastern Front. They were used for frontal patrols and logistics on the open prairies (steppes), which they knew well. The first Cossacks units were formed as early as 1936; by 1942 there were 17 Cossack corps units in the Red Army (as opposed to two in the German forces). Later these corps units were increased in size and reduced to eight. Their distinction in battle eventually led all to be merited as Guards. Oka Gorodovikov formed 49 Cossack cavalry divisions during the war. Many ethnic Cossacks served in other divisions of the Red Army and in the Navy, including Boris Shaposhnikov, Markian Popov, Aksel Berg, Arseniy Golovko, Oka Gorodovikov, Lev Dovator, Pavel Belov, General Dmitry Karbyshev, Dmitry Lavrinenko, pilot Grigory Bakhchivandzhi and engineer Fedor Tokarev. A Cossack detachment of the 4th Guards Corps marched in Red Square during the Moscow Victory Parade of 1945.
A substantial number of Cossacks served with the Germans, in response to the harsh repressions and genocide that their families had suffered under the policies pursued by Joseph Stalin. Like other people of the Soviet Union who suffered persecution under Stalin, some Cossacks mistakenly greeted the advancing German army as "liberators" from Stalinism.
While some Cossacks in German service were former White Army refugees or related to them, many Soviet citizens, including rank-and-file Cossacks, defected from the Red Army to join the "Cossack units" of German armed forces. Native Cossacks usually served as officers. As early as 1941, the German leadership formed the first Cossack detachments from prisoners of war, defectors and volunteers. The Dubrovski Battalion formed of Don Cossacks in December 1941 was reorganised on July 30, 1942 into the Pavlov Regiment, numbering up to 350 men. The Germans used Cossacks for anti-partisan activity in the rear of the German army.
The Cossack National Movement of Liberation hoped to gain an independent Cossack state, to be called Cossackia, after the war. In 1943, after the 1st Cossack Division was formed under the command of General Helmuth von Pannwitz, Cossack émigrés such as Andrei Shkuro and Pyotr Krasnov took leading positions in the movement. The 2nd Cossack Division, under the command of Colonel Hans-Joachim von Schultz, formed in 1944, existed for a year. Both Cossack divisions were made part of the XV Cossack Cavalry Corps, totalling some 25,000 men. They wore regular Wehrmacht uniforms and not Waffen-SS ones, as has occasionally been incorrectly alleged. Although in 1944 General von Pannwitz accepted loose affiliation with the Waffen-SS in order to gain access to their supply of superior arms and equipment, together with control over Cossack units in France, no pagan SS features had ever been implemented to respect the Christianity of Cossacks and the Corps command, structure, uniforms, ranks, etc. remained firmly Wehrmacht.
The Corps contained regiments of different Cossack groups, who were Don, Kuban, Terek and Siberian Cossacks who had been fighting Tito's guerrillas, the Ustashi and Domobranci in the former Yugoslavia. At the end of the war in 1945, they conducted a fighting retreat north-eastwards over the Karavanken Mountains into Carinthia, where they surrendered to the British Army in Allied-administered Austria. They hoped to join the British to fight Communism. At the time the Cossacks were seen as Nazi collaborators and they were reported to have committed atrocities against resistance fighters in Eastern Europe. As part of Operation Keelhaul, the British returned Cossack prisoners of war to Russia.
On 28 May 1945, told they would be resettled in Canada or Australia, the Cossacks were transferred to SMERSH custody at the Soviet demarcation line at Judenburg. Also included in the transfer were civilian members of the Kazachi Stan, consisting of old folk, women, and children, as well as about 850 German officers and non-commissioned officers of the Corps. At the end of the war, the British repatriated between 40 to 50 thousand Cossacks, including families of military, to the Soviet Union. Many of those were reported as never having been Soviet citizens. An unknown number were subsequently executed or imprisoned. This episode is widely known as the Betrayal of the Cossacks.