In eastern Ukraine (Donbas) most of the Russian backed rebels are actually disorganized, discouraged and not all that effective. Interrogations of captured rebels indicate that there are many different factions, some of them not even from Ukraine. The most colorful of these foreigners are the “Cossack” units from southern Russia. The Cossacks are very nationalist, aggressive, persistent, independent minded and really keen on rebuilding the Russian empire (which is what Cossacks were invented for centuries ago). Actually the Cossacks attract a wide array or rebellious Russians and many of those in the Donbas are not keen on taking orders from anyone. So one reason for sending more Russian troops in is to try and get the Cossacks to do what Russia, not Cossack leaders, want. That’s not the only problems the Russians are having with these guys. Cossacks are a number of things, including righteous. Although poorly treated by the communists, the Cossacks are believers in collectivism and tend to be very hostile to corrupt leaders they come across. This has caused problems in Russia and again in Donbas because some of the local separatist rebel leaders are, for want of a better term, quite corrupt. Cossacks accuse these leaders of stealing Russian aid and taking care of themselves and their armed followers rather that sticking with the goal of an independent Donbas or incorporation into Russia. What is feared is the troublesome and righteous Cossacks triggering a civil war among the rebels.
The Cossacks were welcome arrivals when they showed up in 2014, because the original local Donbas rebels quickly lost their enthusiasm when their uprising triggered a nationalistic fervor throughout Ukraine and inspired Ukrainian troops and armed volunteers to fight a lot harder than the rebels expected. Russia, which sponsored and encouraged the rebels from the start soon found that the only way they could take territory was to send in Russian troops and heavy weapons (tanks, artillery, rocket launchers, missiles). The special operations units (Spetsnaz) were the best for this because these guys knew how to pretend (that they were Ukrainian rebels) and were very effective fighters. But there not enough of them available and regular Russian troops (which are mainly conscripts) had to be sent in as well, especially for support (transport and supply) functions. Soon it was Russian troops leading in any offensives with the local rebels and other volunteers (like the Cossacks and such from Russia) handling occupation of newly conquered territory. These imported rebels and conscript troops did not do much to hide who they were and where they were from.
Elsewhere in Russia the Cossacks have been less trouble and more useful. The Cossacks are also being used to try and replace all the Russian inhabitants of the Caucasus who have been driven out by nationalist rebels and Islamic terrorists. Russia had, over the last two centuries, encouraged ethnic Russians to settle in the Caucasus in order to help maintain Russian control of an often-hostile native population. With the collapse of the empire (the Soviet Union) in 1991 there was no money left to subsidize the ethnic Russians in the Caucasus. That, as much as the anti-Russian attitudes of the natives, prompted most Russians to leave. Now the Russian government is using an old solution to get more ethnic Russians back into the Caucasus; it’s sending in the Cossacks.
The Cossack people are ethnic Russians with a distinct language and culture (not quite Russian) and strong ties to the Russian Orthodox Church. There are about seven million Cossacks in Russia, Ukraine, and other portions of the former Soviet Union. Their involvement in Russian wars goes back centuries. During Tsarist times, Cossacks formed special cavalry units in the Imperial Russian Army, as well serving as instruments of state repression. The Russian Empire had a special arrangement with the Cossacks whereby, in exchange for frontier land, greater political autonomy, and special social status, Cossacks contributed military forces, providing their own horses, weapons, and equipment. Unique, exclusively Cossack military formations have been a staple of Russian history in one way or another for many, many centuries. Cossacks were also notorious for their willingness to do the czar’s dirty work, especially in the Caucasus.
Opinions on the actual military value of Cossack units is widely divided, as are opinions of the Cossacks themselves. At many points in Russian military history the Cossacks proved themselves to be determined and fierce, sometimes to the point of recklessness, warriors, and there are examples of entire Cossack units fighting to the death against impossible odds. During the Napoleonic Wars and the French invasion of Russia in 1812 Cossack units, mostly as light cavalry, operated extremely effectively as scouts and raiders, harassing the retreating French army mercilessly. Their performance against regular troops in open battle was less than great, but then that wasn't their role anyway.
On the other hand Cossack units, from the days of Peter the Great until modern time, have a well-deserved reputation for brutality, anti-Semitism, and looting. They have always been notoriously difficult to control, with Russian officers in past wars becoming frustrated and enraged with drunken, mutinous Cossack soldiers. During the Russian Civil War, Cossacks fought for both sides, especially for the anti-Communist White forces, but they were often divisive, unreliable, and preoccupied with looting and general destruction. Also, many Russians regarded them as potential rebels, given their unruly history, large numbers, and independent-minded spirit, and those familiar with history know that for a two century period, every major rebellion against the Russian Empire was led by Cossack troops. During the Soviet period, Cossacks were among the many ill-treated minorities, having their distinct culture and language suppressed by the Communist authorities.
Since the 1990s Cossacks are once again involved in Russian conflicts. In an effort to bolster national pride and recover some of the distinct Russian heritage that was suppressed during 70 years of Soviet rule Russia has officially brought back the formation of exclusively Cossack military units, and in a big way. This has accompanied a general explosion of Cossack culture in recent years. Cossack military schools have been established, where student ages 10 to 17 attend classes in army fatigues and learn military tactics alongside regular academic subjects. An entire Kuban Cossack Army, headquartered in Krasnodar, has been established and is incorporated as a unique, but fully integrated, part of the Russian Army. The Russian Minister for Cossack Affairs, general Gennady Troshev (until his death in 2009) was a Cossack himself and had been instrumental in the remilitarization of the Cossack society.
Irregular Cossack paramilitary units fought on the Russian/separatist side in the 2008 Russo-Georgian War, which saw South Ossetia taken from Georgia and made a de facto part of Russia. Cossack volunteers by the hundreds mobilized during the Georgian attack of South Ossetia and crossed the border to engage Georgian forces. Cossacks in nearby North Ossetia apparently organized a relatively efficient and rapid system for clothing, equipping and transporting their paramilitaries into the breakaway province to feed them into combat. Cossack fighters entered South Ossetia by bus, having been issued combat uniforms and gear on the way to the border, and were issued small arms and light weapons once they arrived at the border. Cossack volunteers formed the second major paramilitary force in the war, the first being the South Ossetian militias. According to reports, the Cossack forces fought with dogged determination. Russian army commanders noted the effectiveness of the Cossacks in Georgia which appears to be why the Cossacks showed up in Donbas so quickly. The big difference is that Russian forces soon withdrew from most of Georgia while in Donbas the conflict has gone on for months.
Paramilitary forces and semi-standing armies of "volunteers", of various ethnic and political lines, are a major part of armed conflict in Russia and the former Soviet Union, particularly among Slavic ethnicities. Such forces exist in disputed territories between Armenia and Azerbaijan, where a majority of ethnic Armenians live in the unrecognized Republic of Nogorno-Karabakh. The Nogorno-Karabakh Defense Army is the formal defense force of the Nogorno-Karabakh Republic. Similar forces exist in both breakaway republics of South Ossetia and Azkaban. Now Cossacks are trying to settle down in eastern Ukraine (parts of which were once “Cossack lands”).
The new Russian policy is to encourage, with cash investments and monthly payments to adult Cossacks willing to undergo military training, the establishment of Cossack communities in the Caucasus. These towns and villages would be in touch with the surrounding non-Cossack population and able, if there were problems with the natives, to defend themselves until Russian reinforcements show up. That’s a strategy that is centuries old and Russia sees it as succeeding again. The Caucasus natives have a long-standing dislike for the Cossacks, but at the same time fear and respect them, especially when the Cossacks are acting as paramilitary forces. But in Ukraine the Cossacks often led Ukrainian rebellions against the Russian government. That distant memory is now being reexamined in Moscow and the policies of how to use the Cossacks being reconsidered.