STEPHEN BIDDLE
For months, commentary on Ukraine focused on stalemate and the prospect that changing technology augured a looming age of defense dominance in warfare. Russia’s assault on Kyiv had failed. Its assault on Odessa had ground to a halt well short of the city. Its offensive in eastern Ukraine had stalled. Ukraine’s much-anticipated counteroffensive in the south had made limited early progress, and Ukraine’s defense minister had said that Ukraine lacked the materiel to take ground on any large scale. A spring and summer of intense combat had produced almost no meaningful change in territorial control.
Many saw this pattern as a harbinger of profound change in warfare. In this view, tanks, piloted aircraft, surface warships, and massed infantry formations were now just large, slow targets for small, cheap, precision weapons. As weapons have grown more accurate and lethal, the argument holds, concentrated formations operating in the open had become unable to survive long enough to overrun enemy positions. Surprise had become impossible in the face of long-range surveillance by drones and airborne radar. Breakthrough had thus become unachievable, and exploitation would be impossible even if breakthrough were not. In the 21st century, the kinds of sweeping, decisive offensive maneuver seen in the German conquest of France in 1940, or the Six Day War of 1967, or Operation Desert Storm in 1991 were thus a thing of the past, many claimed.
This analysis now seems premature. Ukraine’s September counteroffensive in Kharkiv recaptured more than 6,000 square kilometers of Russian-held ground in less than two weeks. Kharkiv was followed by substantial Ukrainian advances in northern Kherson in early October and the recapture of the rest of the oblast west of the Dnipro in mid-November. Tanks and other armored vehicles played a major role in both offensives, and further gains look likely. This sudden change in battlefield fortunes has pushed Russian President Vladimir Putin into a politically risky partial mobilization. Recent events certainly seem inconsistent with an expectation of epochal change to a technologically determined era of defense dominance.
What, then, actually is happening in Ukraine and what does the pattern of outcomes mean for the future, and for defense planning in the United States and elsewhere? Humility is in order, of course. Both the stalemate of the summer and the breakthroughs of the fall surprised many, and there may be more surprises in store. Many new technologies are in use, and both sides are learning and adapting rapidly. So conclusions drawn now, in the midst of the fighting, must always be tentative and preliminary.
But perceptions take root early all the same, so it is important for analysts to shape these as accurately as possible even while events unfold. And for now, the best understanding is that offensive maneuver is far from dead. In fact, the patterns visible so far actually look a lot more like the past than like any new model of revolutionary transformation. And the policy prescriptions that follow from the transformation interpretation look correspondingly premature: calls for retiring tanks in favor of drones, or reframing military doctrine to avoid offensive action, are a poor fit to the actual pattern of combat observable to date in Ukraine.
Variations in Force Employment
This pattern has involved both successful offense and successful defense from the beginning of the war. Russia’s initial invasion was poorly executed in many ways, yet it gained over 110,000 square kilometers of ground in less than a month. Ukraine’s Kyiv counteroffensive retook over 50,000 square kilometers in March and early April. Battle lines then mostly stabilized in spite of heavy Russian offensive pressure in late spring and summer before Ukraine’s fall counteroffensives. But whereas the September Kharkiv counteroffensive broke through quickly and drove the Russians from large parts of the eastern theater in days, Ukraine’s Kherson counteroffensive made only limited progress for over a month in spite of major efforts and heavy Ukrainian casualties.
These variations are hard to square with any technologically determined epoch. All of this – both the breakthroughs and the stalemates – has occurred in the face of small, cheap, precise 21st century weapons. Tanks played prominent roles in both the breakthroughs and the stalemates.
The real difference appears to have been major variation in force employment at the tactical and operational level, coupled with a mass mobilization of Ukrainian reservists, few of whom have been armed with precision weapons. Defenses that were initially undermanned (on Ukraine’s northern front) and shallow and unprepared (on Ukraine’s southern front), enabled rapid advances. Russians who initially sacrificed security for speed in these advances moved in unsupported road-bound columns that outran their logistics and suffered heavy losses that then left them vulnerable to counterattack against their overextended positions.
Conversely, defenses that were deep and well-prepared, such as Ukraine’s positions in the east, were much less vulnerable and could be pushed back only by attackers who advanced cautiously with heavy fire support. As Ukrainian mobilization produced an army large enough to fill gaps and constitute a meaningful reserve, an undersized Russian invasion force was compelled to adopt defensive postures in Kherson and Kharkiv and to make choices in the allocation of inadequate forces. They chose to defend deep, prepared positions in Kherson with their better units and to accept risk in Kharkiv with thinner, unsupported defenses manned by lower-quality units while continuing their slow-moving attrition offensive toward Bakhmut.
This produced slow progress for the Russians at Bakhmut and in the initial Ukrainian offensive at Kherson, but breakthrough and rapid advance by the Ukrainians at Kharkiv. Russian logistical vulnerability on the west side of the Dnipro in Kherson contributed to Ukrainian progress there in early October and the fall of Kherson city in November. But throughout, it has been difficult for either side to make rapid headway or produce clean breakthroughs against deep, prepared, well-motivated defenses supported by meaningful reserves and viable supply lines. By contrast, both sides have been able to make much faster progress against shallow defenses without significant reserves behind them, and especially so when the defenders lacked commitment to the cause for which they fought and when supply lines could not be maintained.
Repeating Lessons From the History of Land Warfare
This should not be surprising. In fact, it encapsulates the modern history of land warfare. Since at least 1917 it has been very hard to break through properly supplied defenses that are disposed in depth, supported by operational reserves, and prepared with forward positions that are covered and concealed (and especially so without air superiority). This combination enforced the great trench stalemate on the Western Front in World War I.
But this pattern has persisted long after that. In the popular imagination, World War II replaced trench stalemate with a war of maneuver. But mid- and late-war offensives against properly prepared defenses commonly produced results that looked less like blitzkrieg and more like the slow, costly, grinding advance of the Hundred Days offensives of 1918. Concentrated, armor-heavy attackers at the Mareth Line in 1943, Kursk in 1943, Operations Epsom, Goodwood, or Market Garden in 1944, the Siegfried Line in 1944, or the Gothic Line in 1944-45 all failed to produce quick breakthroughs and devolved into slow, methodical slogs at best, and “death rides of the armored divisions” (as historian Alexander McKee characterized Goodwood) at worst.
Nor did this pattern end in 1945. Iraqi armored offensives bogged down against even moderately deep Iranian defenses at Khorramshahr and Abadan in 1980-81, and Iranian offensives failed to penetrate prepared Iraqi defenses in depth at Basra in 1987. More recently, the 1999 battle of Tsorona between Ethiopia and Eritrea, the Israeli invasion of South Lebanon in 2006, and Georgia’s invasion of South Ossetia in 2008 all showed a similar pattern wherein mechanized offensives made slow progress when they encountered deep, prepared defenses.
Of course there have also been dramatic offensive successes since 1917. The German invasion of France in 1940 knocked the French out of World War II in a month. The German invasion of the Soviet Union in 1941 destroyed over 100 Soviet divisions and advanced to the gates of Moscow in a season. Operation Cobra in 1944 broke through German lines and retook most of metropolitan France in a month. The Israeli invasion of the Sinai in 1967 triumphed in just six days. The American counteroffensive in Operation Desert Storm in 1991 evicted the Iraqis from Kuwait in 100 hours of ground fighting. The 2020 Azerbaijani offensive in Nagorno-Karabakh drove the Armenians from the Aras River Valley in less than two months.
Force Employment and Combat Outcomes
But this pattern does not suggest any epochal transition from defense dominance in World War I to offense dominance in World War II and after to some new era of defense now dawning in the 21st century. Instead, as I argue in my book, Military Power: Explaining Victory and Defeat in Modern Battle, the reality of war since at least 1917 has been a consistently powerful relationship between force employment — the tactics and operational methods adopted by the combatants — and combat outcomes in the face of progressively more lethal firepower. Where defenses have been deep, supported by operational reserves and well-prepared at the front, quick blitzkrieg success has been all but impossible over more than a century of changing technology. Well-trained, astutely employed attackers with numerical superiority can take ground against such defenses, but slowly and at great cost. Clean breakthroughs followed by exploitation and the decisive conquest of large theaters has long required a permissive opponent — that is, a defender who lacks depth, who has failed to withhold a meaningful reserve, who has failed to ensure cover and concealment at the front, and, often, whose troops lack the motivation to fight hard in the defense of those positions.
Defenders and attackers have varied widely over the last century in their ability to implement these methods. Deep elastic defenses are complex and difficult to manage. And the kinds of combined arms techniques needed to make even slow headway against them are at least as hard to execute in the field, especially where air and ground forces must cooperate closely. Often, the best single predictor of outcomes in real warfare has thus been the balance of skill and motivation on the two sides. Where both sides can handle the complexity of modern warfare and use their materiel to full potential, the result has often been slow, grinding battles of attrition that look more like 1918 than 1940 or 1967. But where defenders, in particular, lack the skills or the motivation to master complex modern warfare and present shallow, forward, ill-prepared or poorly motivated defenses, then astutely-led, well-trained attackers have been able to exploit defenders’ failings and produce lightning victories — whether in 1940 or in 1967 or in 1991.
The contours of combat so far in Ukraine give little reason to expect some coming transformation of this pattern. Rapid early ground gains against shallow, forward defenses followed by successful counterattacks against overextended attackers are far more similar to the past than different from it — nor is subsequent offensive frustration against deeper, better prepared defenses a radical break from historical experience. Of course there is a range of new equipment in Ukraine, from drones to anti-tank guided missiles to long-range surface-to-air missiles and more. But every war brings new equipment. And most wars bring claims that this new equipment is revolutionizing warfare to radically favor attackers or defenders — certainly this was a major feature of the debates following the 1973 Arab-Israeli War, the 1991 Persian Gulf War, the 2001 invasion of Afghanistan, or the 2020 Nagorno-Karabakh War. For Ukraine so far, neither the fighting nor the debate over the fighting has posed any radical departure from these tendencies.
Long Live Offensive Maneuver
What, then, does this mean for the U.S. military looking forward? Part II of this series considers this in more detail, but several broad, tentative lessons are worth highlighting first.
First, offensive maneuver is apparently far from dead. Even in the face of modern weapons, breakthrough is still possible, and especially so when astute offensive operations on interior lines pose dilemmas for thinly stretched defenses like those of the Russians in Kherson and Kharkiv since mid-summer. Those offensives would have been even more successful with improved Ukrainian training and equipment, but Ukraine’s ability to succeed with what they have is a powerful demonstration that offensive maneuver has not been rendered impossible by new technology.
But second, while offensive breakthrough is still possible under the right conditions, it remains very hard to accomplish against deep, prepared defenses with adequate supplies and operational reserves behind them. This is not a novel feature of new technology — it is an enduring consequence of the post-1900 lethality of ever-evolving weapons that has been observed repeatedly over more than a century of combat experience. Exposed defenders are increasingly vulnerable to long-range weapons and sensors, but covered and concealed positions remain highly resistant to precision engagement. Shallow, forward defenses can be ruptured with well-organized combined arms attacks, but deep defenses with meaningful reserves behind them still pose much harder problems for attackers. Overextended positions without secure supply lines can be overwhelmed, but consolidated positions with viable logistical support are still much harder and more costly to overcome.
Third, neither shallow, vulnerable defenses nor deep, robust ones are universal features of modern war. Both have occurred regularly since 1900, and both have occurred, at various times and places, in Ukraine since February.
And this in turn casts doubt on the advisability of redesigning modern militaries around an assumption that new technology has made effective offensive maneuver either impossible or available on demand. Successful offense has long been very difficult, and it has normally required both demanding preparations and a permissive defender. But it offers decisive outcomes when conditions allow it, and such conditions recur with enough frequency to suggest that its demands are worth meeting.
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