Home / Articles / How the Battle for the Donbas Shaped Ukraine’s Success
Ukraine’s successes in Kherson and Kharkiv were largely a result of the losses it inflicted on the Russian military in the Battle for the Donbas in the spring and early summer.
Attrition enabled successful maneuver warfare.
The course of the war in 2023 will depend heavily on external support and how well Russia integrates mobilized soldiers.
As the Russian-Ukrainian War enters the winter, Ukrainians have reason to be cautiously optimistic about the course of the war. Following a strategic offensive at the end of August in multiple regions, Ukrainian forces have retaken nearly all of Kharkiv Oblast, parts of the Donetsk Oblast, and the right bank of Kherson Oblast. Several factors enabled Ukrainian offensives in Kherson and Kharkiv, but much of that success stems from the earlier Battle for the Donbas. Russia’s advances in the Donbas, from April to July, proved to be a pyrrhic victory, tactical successes at the expense of strategic vision. Russia expended valuable manpower and artillery ammunition, while Ukraine pursued a defense-in-depth strategy. By September, NATO arms deliveries had reduced Russia’s critical advantage in artillery and Moscow didn’t have sufficient forces or ammunition to hold the territory occupied, which set the stage for Ukraine’s successful offensives.
The battle for the Donbas bled the Russian military of manpower, at a time when it lacked the forces to both hold captured territory and continue offensives. The Russian military offset this deficit by dramatically increasing its rate of artillery fire. This burned through Russia’s second most critical resource, artillery ammunition. The net effect of both decisions showed itself in the fall, when Russia lacked the manpower to defend Kharkiv and the artillery ammunition to hold defensive lines in Kherson. Since then, Moscow has been able to compensate for the manpower deficit with mobilization, but recent fighting in Bakhmut suggests Russian forces are conserving ammunition, no longer firing at the rate they did in earlier phases of the war.
The most important inflection point of this war was at the end of March when the Kremlin realized it could not seize or encircle Kyiv and achieve its maximalist objectives. The Russian military still had several advantages over the Ukrainian military at this point, but it didn’t have the forces to continue advancing in most directions and had sustained heavy personnel and equipment losses. Ukraine and Russia were negotiating, and Ukrainian officials had signaled a willingness to make certain concessions; however, the two sides never reached an agreement. It isn’t completely clear how close these negotiations came to a final deal, but when Russia pulled its forces from northern Ukraine—leading to the discovery of the atrocities committed in Bucha and other towns occupied by Russian forces—the immediate prospects of further negotiations ended. Russia’s best option was to end the war at this point while extracting limited concessions. Once Russian forces no longer threatened Kyiv and other cities in the north, Russia’s bargaining position and ability to coerce Ukraine decreased substantially.
After the initial phase of Russia’s invasion failed in February and March, the chief of the Russian General Staff’s Main Operational Directorate, Col. Gen. Sergei Rudskoy, announced that Russia would focus on seizing all of the Donbas. Russian forces retreated from the Kyiv, Chernihiv, and Sumy Oblasts, and were redeployed to Kharkiv, the Donbas, or southern Ukraine.
However, there was an obvious problem with Moscow’s new strategy. Even if Russian forces managed to seize the entire Donbas region, there was little reason to believe that would force Ukraine to concede and end the war on Russian terms. Instead, the Kremlin’s thinking was increasingly characterized by strategic procrastination and wishful thinking. Moscow appeared to focus on its minimal war aims, without an understanding of how they would lead to achieving long-term strategic goals, or how the war might end. Despite a structural mismatch of military means to political ends, and no war termination strategy, Russian leadership committed to a campaign focused on occupying more territory in the Donbas, while trying to hold everything else. This approach consumed Russian manpower and ammunition at an unsustainable rate, setting the stage for successful Ukrainian offensives in the fall, and may well prevent the Russian military from restoring offensive potential even after this winter.
During the initial invasion, Russia committed more than 80 percent of its permanent readiness battalion tactical groups as well as units from the Russian National Guard (Rosgvardia) and the Russian proxy Luhansk and Donetsk People’s Republic’s army corps (their forces are essentially part of the Russian military). This meant the Russian military only had a limited reserve if the invasion force was unable to quickly achieve Russia’s objectives. This was a high-risk, heavily leveraged operation, with no discernible hedge in the event things went badly wrong. In comparison, the United States invaded Iraq in 2003 with approximately 40 percent of its maneuver battalions, which left it with a large enough initial reserve for a more sustainable rotation.
When Russia’s regime-change plans went awry, the Russian military decided to send additional battalion tactical groups from critical locations, such as Kaliningrad, Abkhazia, South Ossetia, and Tajikistan, leaving Russia vulnerable if crises broke out along its borders. This consumed much of the remaining active force. Many of these battalions began the war understrength and then sustained heavy losses from April through June. As the Russian military burned through officers, and enlisted professionals, the number of officers and soldiers who refused to fight grew once many of them discovered that the punishment would be minimal. As many as 20–40 percent of soldiers in some units refused to return to Ukraine when they retreated from northern Ukraine back to Russia. The problem with refuseniks expanded over the course of the spring and summer. Combined with high levels of attrition, by September this resulted in Russian units having barely 20 percent of their expected manning levels in Kharkiv.
All of these problems began much sooner. Most Russian battalion tactical groups were likely at less than 50 percent of their authorized strength by May during Russia’s attempts to seize more of the Donbas. This meant that the Russian military faced a serious manpower problem when it began that campaign without a workable method for generating additional forces. Instead of adopting a strategy that took into account these limitations, Moscow decided to throw its forces into a costly, attritional struggle in the Donbas without a clear strategy for ending the war. Russia’s tactical successes in the Donbas in May and June would lead to a strategic failure in the fall. Despite these issues, Russia’s strategy in the Donbas might have succeeded without increased foreign support to Ukraine in the late spring and early summer. Ukraine was significantly outgunned in May and June, and its position would have been far more precarious if it had not begun to receive substantial deliveries of howitzers and ammunition, which continued throughout the summer and fall. Moscow may have misjudged Western commitment to Ukraine during this phase, since Washington and other NATO members provided little heavy equipment before the spring. Nonetheless, Russia did not appear to change its strategy as Ukraine began to receive and effectively employ these artillery systems.
Russia had few good options to ameliorate its manpower issues, and piecemeal solutions were going to result in a steady degradation of the force. Unlike enlisted servicemen in the US military, Russian conscripts are not trained at centralized schools, but instead mostly by their units. Yet, Russia invaded Ukraine with the vast majority of its permanent readiness units, and many units likely pulled their training officers and non-commissioned officers to make up for shortages. This meant the Russian military was in a poor position to recruit and train new units and was not well-designed to fight a large-scale protracted war without mobilization. While some suspected Vladimir Putin might order a partial mobilization in May, he appeared to be under the belief that the Russian military could grind its way to victory in the Donbas without such drastic measures. This was another case of political procrastination, as Russia’s options went from bad to worse.
Instead, the Russian military adopted four types of stopgap measures to sustain the war: forming reserve battalions with much lower manning levels, creating regional volunteer battalions, forcibly mobilizing men in occupied parts of Luhansk and Donetsk, and increasing dependence on organizations like the Wagner Group. In order to compensate for its understrength battalion tactical groups, Russia began to recruit volunteers to serve in the Russian military, National Guard, and Russian proxy Luhansk and Donetsk People’s Republics units in the spring. Many of these volunteers previously fought in the Donbas or had military experience and generally signed short three- or six-month contracts. The most ideologically supportive or financially desperate men—the contracts were generally well above the average salary in many cities—signed contracts to fight, but most received less than a week of training before deploying to Ukraine.
Russia also began to rely more heavily on the Wagner Group and other semi-private paramilitary groups. Unlike the Russian military, which depends on conscription for its recruiting needs, Wagner had an established infrastructure across Russia to recruit volunteers and to train and equip them for various jobs. Russia also chose to mobilize adult men in the occupied areas of the Donbas early in the war. As the spring and summer progressed, the force fighting for Russia was increasingly composed of volunteers, mobilized men, and private military contractors. By August, when Ukraine began its offensives, Russia’s front lines were often manned by mobilized Russian proxy Luhansk and Donetsk People’s Republics units, Rosgvardia units not equipped for conventional war, or understrength Russian military units composed of volunteers who had signed contracts after the war began. It was not a professional force.
Although the Russian military still had a number of conventional advantages in April, Russia’s revised military objectives gave its commanders little room for operational art or creativity. Instead, the Russian campaign in the Donbas would often consist of frontal assaults on entrenched positions in the most fortified part of the country. Russian forces compensated by leaning heavily on their significant artillery advantage. When it achieved its greatest successes in May and June, the Russian military was firing substantially more artillery rounds each day than the Ukrainian military (although daily fire rates of 50,000–60,000 seem unrealistic figures). Despite this advantage, Russia’s advance was still slow and costly, because the military lacked the forces to conduct maneuver warfare or maintain momentum from any breakthrough. Outgunned Ukrainian soldiers holding the defensive lines in the Donbas in the spring and early summer were instrumental to Ukraine’s future offensives. They ensured that any Russian offensive would involve heavy losses, and they slowed down Russia’s advance, which bought critical time as Ukrainian troops trained on and received increasingly sophisticated NATO artillery systems and high mobility artillery rocket systems (HIMARS). Consequently, Ukraine’s successes in Kharkiv and Kherson in the fall were due to the losses sustained by Russia in the spring.
The arrival of HIMARS had an almost immediate effect on the battlefield. Russia’s logistics system is fairly antiquated and centralized, which meant it still relied heavily on large ammunition depots. Ukrainian HIMARS began to target these depots with explosive results. They also began to strike Russian command posts, and they were likely responsible for the strikes on the headquarters of Russia’s 20th Motorized Rifle Division and 106th Airborne Division in July. The destruction of these ammunition depots didn’t stop Russian artillery, but it significantly reduced the number of rounds they could fire every day. Additionally, Ukraine’s inventory of Western artillery would prove to be more effective at counter-battery fire, particularly once Ukraine began to receive precision-guided artillery rounds like the Excalibur. Since artillery was Russia’s greatest advantage during the Battle of the Donbas, the arrival of HIMARS and Western artillery was critical.
Ukraine’s ability to effectively employ HIMARS and artillery depended heavily on the success of its air defenses to prevent the Russian Air Force from targeting them or conducting interdiction missions. Continued attrition also reduced Russia’s manpower advantage. Ukraine mobilized a substantial number of civilians at the beginning of the war, but not all were effectively trained and equipped. However, by the late summer, much of Russia’s force was not professional or well-trained either. These factors meant that Russia’s advances in the Donbas slowed dramatically after Lysychansk was taken at the beginning of July. By that point, it was clear that Russia had neither a sufficient advantage in artillery nor maneuver forces to achieve significant successes. The Kremlin had reached another inflection point.
Moscow decided to reinforce its position on the right bank of Kherson in July and August with elite Airborne Forces units, as well as Eastern Military District units that were based along the Izyum front in anticipation of an expected Ukrainian offensive. By moving those forces to Kherson, Russia was tacitly acknowledging it would no longer be able to advance much in the Donbas. The decision also left Russia’s forces defending in Kharkiv and Zaporizhzhia at greater risk since they would have fewer reserves available in case of a Ukrainian offensive. By the end of August, Russia also began to deploy its 3rd Army Corps, which was a new type of volunteer unit. Unlike previous volunteers who received minimal training and often served as combat replacements, the 3rd Army Corps was composed of regional volunteer battalions supported by local governments that would spend a month at the Mulino and Totskoye training ranges in Nizhny Novgorod and Orenburg before deploying. The 3rd Army Corps also received modern BMP-3, T-80BVM and T-90M tanks, and other equipment. But it failed to meet its personnel targets, and there wasn’t a clear plan for raising additional volunteer forces after it was deployed to Ukraine. Once again, Russia developed a short-term plan without a long-term vision of victory. The 3rd Army Corps was deployed to Ukraine at the end of August, but it was unable to stem Ukraine’s offensives. Putin still declined to declare a general mobilization.
Ukrainian Breakthrough in Kharkiv
The extent of Russia’s manpower issues became clear after Ukraine’s successful offensive in Kharkiv. Captured documents and Russian Telegram channels indicated that many Russian military units holding the front lines were substantially understrength—including two units at less than 25 percent of their authorized strength—and had lost critical equipment, such as counter-battery radars, which had not been replaced. In particular, Russian Telegram channels emphasized the lack of infantry soldiers. Russian military correspondent Alexander Kots said that he knew of Russian brigades with only sixty infantry soldiers left when mobilization was announced. In addition, Ukraine captured a number of soldiers from different specialties who were serving in combat roles, such as a sailor who claimed he had served at a naval munitions storage base before being assigned as part of a tank crew with only minimal training as well as soldiers from Russia’s Strategic Missile Forces. In another case in Mykolaiv Oblast, Ukrainian forces captured a Russian paratrooper who served in a tank with a member of Wagner and a mobilized man from Lukhansk Oblast. There were also cases of militarybandmembers who were deployed and killed during fighting as far back as March. These anecdotes were similar to how the Russian military was forced to pull any available servicemen regardless of their specialty to man piecemeal units to fight during the wars in Chechnya. To sustain its repeated assaults on Bakhmut, Wagner began to recruit prisoners and sent them to the front line as well at the end of the summer.
Russia simply did not have sufficient forces to hold an expansive front in Ukraine. Russian units in Kharkiv were convinced in July that Ukraine would conduct an offensive in the region, and the intensity of the fighting increased throughout July and August, which began to take an increasing toll on Russian forces. Recovered letters also showed that a number of Russian soldiers based in Kharkiv requested to take leave a week prior to Ukraine’s offensive. Indeed, several RussianTelegram channels run by Russian fighters or correspondents embedded with Russian forces were warning for much of August of a Ukrainian buildup in Kharkiv, and multiplechannels warned about a buildup near Balakliya one week prior to the offensive, which is where Ukraine’s breakthrough occurred. There were multiple indications that Ukraine was about to conduct an offensive and that Russian forces in Kharkiv were vulnerable. Nonetheless, the Russian military appears to have only taken minimal, if any, steps to prepare. Most likely, Russian political leadership refused to allow a retreat, but the military simply did not have the forces or equipment available to reinforce the region.
Ukraine’s Kharkiv operation was a well-planned and executed combined arms operation, but it benefitted significantly from the fact that Russian forces were simply in no position to defend that region. In brief, combined arms maneuver was possible because of the high levels of attrition suffered by Russian forces in the run-up to the offensive and the lack of cohesion among remaining units. Ukrainian forces infiltrated past Russian lines and achieved a breakthrough at a weak point in Russia’s lines that was reportedly held by mobilized Luhansk People’s Republic forces with Rosgvardia SOBR and OMON—roughly analogous to police SWAT and riot police—in the second echelon. Russian sources, including Igor Girkin, claimed that the LNR forces lacked sufficient heavy weapons and the SOBR servicemen did not knowhow to properly employ heavy weapons, such as automatic grenade launchers, anti-tank guided missiles, and recoilless rifles, and only conducted minimal coordination with the artillery unit in the area. In addition to the poorly-equipped forces holding the front lines, Russia lacked a sufficient reserve in Kharkiv to stop Ukrainian breakthroughs. Russian channels said that Ukraine effectively employed artillery and HIMARS prior to the offensive and conducted a rapid offensive with both heavy tank and mechanized infantry units as well as light reconnaissance, airborne, and special operations forces, which created chaos behind Russia’s lines. Ukraine also pushed ground-based air defenses forward, which prevented the Russian Air Force from stopping the advance. Ukrainian forces rapidly advanced to Kupyansk and then Izyum, forcing Russian forces to withdraw from both towns and most of Kharkiv Oblast.
In contrast, it took Ukraine more than two months to retake the entire right bank of Kherson after beginning its offensive. Ukrainian forces also employed combined arms, armor, special operations forces, HIMARS, artillery, as well as TB2 unmanned combat aerial vehicles in Kherson, but they were unable to achieve a breakthrough until October. However, Russian forces were still able to prevent this breakthrough from leading to a collapse of Russian lines on the right bank. The greatest difference in the two campaigns was the quality and density of Russian forces defending. The forces in Kharkiv were understrength and poorly trained—the Russian Western Military District’s forces have performed the worst in this war—whereas the Russian Airborne Forces in Kherson were more capable and better led, according to Russian channels. Russia built layered defenses in Kherson and the terrain was more open, which made it easier to locate attacking forces with unmanned aerial vehicles and engage them with artillery. In addition, it appeared Russia was using its scarce supply of precision-guided munitions more often in Kherson than elsewhere along the front. This included Russian KUB and Lancet loitering munitions, which are more often employed by Russia Special Operations Forces or Airborne Forces; Iranian Shahed 136/131 (Geran-2) loitering munitions; longer-range LMUR missiles launched from Mi-28MN attack helicopters, which were often used to target Ukrainian river crossings; and Krasnopol laser-guided artillery rounds. Aside from the Iranian unmanned aerial vehicles, Russia tested all these munitions in Syria, and many appear to be relatively effective. However, Russia didn’t possess them in sufficient quantities for such a large-scale war, including enough Orlan-30 unmanned aerial vehicles that can laze targets for Krasnopol rounds.
After Ukraine’s success in Kharkiv, Putin reportedly turned down requests from his generals to pull back from the right bank of the Dnipro. However, Putin acquiesced to their request to begin a general mobilization, and the first mobilized soldiers would be deployed to Ukraine less than a week later. The priority was holding back Ukraine’s advances in Lyman and across the Kreminna-Svatove front in Luhansk Oblast, so Russia deployed mobilized soldiers with minimal training, and Russian Telegram channels shared a number of anecdotes of costly mistakes committed by these untrained units. In Kherson, Ukraine continued to attrit Russian forces while targeting the bridges across the Dnipro River and the ferries that kept Russian forces supplied.
Russia likely could have kept its forces on the right bank of the Dnipro for longer, but those units would have continued to fight at a disadvantage. While Russia’s best troops were stuck in Kherson, Ukrainian forces would continue to advance elsewhere. Additionally, it would take time to properly train and equip mobilized soldiers, unlike those who were quickly thrown into combat. The Dnipro was an obvious natural barrier that could help Russia use its scarce forces to hold its front line across Ukraine. Had Russia pulled back across the Dnipro in July or August and used the river as a barrier, it possibly could have held Kharkiv, or at least made it a more costly offensive.
Nonetheless, Ukraine still had an advantage in precision fires with HIMARS, Excalibur, and other precision-guided artillery rounds. However, Kherson reveals that the overall effect of HIMARS may be overstated, and its impact leveled off after the first two months of use on the battlefield. Russian forces were able to sustain artillery fire, and ultimately to withdraw from Kherson with most of their equipment, despite the threat of interdiction posed by Ukrainian precision fires. Adaptations to HIMARS included displacing logistics hubs out of range, hardening command posts, and introducing decoys to make targeting more difficult. Russian forces in Kherson were holding positions across a river, depending on ferries and a dam crossing point for logistics. Yet the fighting was grinding, with high rates of attrition on both sides. Kherson offers a cautionary tale on the challenge of offensive maneuver against an entrenched opponent with sufficient artillery and air defense.
Russia appears to have conducted a competent withdrawal without sustaining heavy losses, which is possibly a reflection of the improved command and control after Army Gen. Sergey Surovikin was appointed the commander of Russian forces in Ukraine. Surovikin has since used these forces to reinforce the fighting in Bakhmut and Svatove. Russia’s current strategy appears to be focused on buying time to raise a larger force composed of mobilized soldiers with better training and equipment than those who have already been deployed. Russia also began a strategic bombing campaign in early October with cruise missiles and Iranian loitering munition strikes on Ukrainian infrastructure targets—primarily power and water plants—in apparent hopes of disrupting Ukraine’s economy, undermining civilian morale, and raising the costs of the war for Kyiv and its Western supporters. This is an asymmetric response to Ukraine’s advantages on the battlefield, which the Russian military is struggling to match. Consequently, Ukraine has an incentive to continue to try to advance and inflict losses on the Russian military over the winter.
The results in Kharkiv and Kherson give a somewhat conflicted view of Ukraine’s prospects to quickly liberate more territory. Although Ukraine can move forces from Kherson to reinforce other parts of the front, it is unlikely to find Russian defenses as vulnerable as they were in Kharkiv in September. The Russian military will now have a much higher force density to terrain ratio, and can conserve ammunition if it pursues a largely defensive strategy. In addition, Russian forces elsewhere don’t face the same constraints as they did on the right bank in Kherson with a large river behind them in range of Ukrainian HIMARS. Russian forces, including Wagner, have been building additional defensive lines since the Kharkiv offensive. This suggests that further offensives by Ukraine will be more difficult, potentially involving more incremental gains at a higher cost, because the conditions are less propitious than they were in Kherson and Kharkiv.
Ukraine still has a number of advantages, however. The winter will likely present greater issues for Russia than Ukraine, because the gap between units with better discipline and morale becomes greater when the weather is poor. The force fighting for Russia is increasingly involuntary—composed of mobilized men from Russia or Ukraine, short-term volunteers who are forced to continue serving, prisoners fighting for Wagner, and soldiers who previously refused to fight who are now being compelled to do so with the threat of criminal penalties—compared to Ukraine’s better-motivated military. Ukrainian soldiers also have clearer strategic goals than their Russian counterparts and the Ukrainian military’s leadership has proven to be competent and to prioritize troop welfare more than Russia’s. All of these factors are advantages that Ukraine can exploit.
Ukrainian special operations forces will likely play a key role over the winter months, now that Russia has a large coast to defend in the south, and Ukraine will probably make further attempts at offensive operations in the coming months when the ground freezes. As long as Ukraine continues to receive sufficient ammunition, particularly for artillery, and spare parts, it stands a good chance of retaking territory. That said, the conflict may become more attritional, seeing incremental gains instead of breakthrough operations. The question is whether these advantages will prove sufficient for Ukrainian forces to retake territory from entrenched Russian troops in layered defensive positions. Much will depend on how well Russia integrates mobilized soldiers into an effective fighting force and the level of foreign assistance both Ukraine and Russia continue to receive.
Despite numerous examples of poor conditions, minimal training, delayed payments, faulty equipment, incompetent leadership, and other problems (including a mass shooting at a training range), mobilized soldiers are providing Russia with more manpower. They’ve enabled the Russian military to stabilize vulnerable lines and conduct a withdrawal from Kherson. Poorly trained soldiers are of minimal value in offensive operations, as Russian infantry attacks at Bakhmut suggest, but it is easier to train someone to man a defensive position. Even elite units, such as the Russian Airborne Forces’ 331st Airborne Regiment and 155th Naval Infantry Brigade, are receiving mobilized soldiers as combat replacements. This is a significant vulnerability for Russia, but, thus far, mobilized soldiers appear to be more of an asset than a liability, though there is undoubtedly variance. The extent to which Russia can create semi-effective mobilized units or successfully integrate mobilized soldiers into existing units will be an important factor in how effectively Russia can sustain this war, particularly during the winter. If Russia fails to train, lead, and integrate mobilized soldiers properly, Ukraine may find an opportunity to achieve another breakthrough when the weather and ground conditions improve.
Another key factor for Russia and Ukraine is foreign support, especially in terms of artillery ammunition. Potential deals for artillery ammunition from North Korea and unmanned aerial vehicles or possibly surface-to-surface missiles from Iran, would likely affect how long Russia can continue this war. However, Ukraine’s war effort also depends heavily on external material support, which is constrained both by availability and policy restrictions. Ammunition availability might be the single most important factor that determines the course of the war in 2023, and that will depend on foreign stockpiles and production. As it stands, the Russian military will struggle to restore offensive potential, but it can drag out a stubborn defense. Ukraine appears advantaged long term, but the longer the war goes on, the greater the uncertainty, and advantage is not predictive of outcomes.
The views expressed in this article are those of the author alone and do not necessarily reflect the position of the Foreign Policy Research Institute, a non-partisan organization that seeks to publish well-argued, policy-oriented articles on American foreign policy and national security priorities.