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Fortress on the Azov: Re-learning Strongpoint Defense of Urban Terrain in LSCO

  • Published
  • By MAJ Viktor Stoll

As the Western Eurasian Steppe crosses the lower reaches of the mighty Don River it immediately abuts the Tahanrozka Gulf – the eastern most extremity of the Sea of Azov. At the industrial port city of Mariupol, the gulf empties the Don’s sediment-rich waters into the Sea of Azov and onwards through the Kerch Strait and into the Black Sea.  Situated along the northern shore of the gulf, Mariupol has long been known for its economic role in the development of the region since its foundation as a municipality within the Russian Empire in 1778. Laying at the delta of the Kalmius and Kalchik Rivers, Mariupol served as a major entrepot for the distribution of goods and peoples throughout the Pontic Steppe. The milieu of Crimean Greeks, Haskalah Jews, Muslim Tartars, and Zaporozhian Cossacks, along with a variety of Western European traders and industrialists, reflected the great diversity of Ukraine east of the Dnipro River. 

Yet, by 1917, just as Mariupol was emerging as a major port for trade in coal and steel of the Donbas region, disaster struck in the form of the Bolshevik Revolution. The region was home to the anti-Bolshevik White Russian Movement and following the defeat of the Whites’ Don and Volunteer Armies in 1919, Mariupol and its surroundings suffered from nearly two decades of Soviet persecution through Soviet policies like “De-Cossackization” and Joseph Stalin’s Holodomor famine (1932-1933).  During World War II, the city was nearly destroyed in intense urban fighting between the Red Army and German Wehrmacht. Now, nearly eight decades later, Mariupol is again on the front lines of large-scale combat operations (LSCO), its inhabitants are suffering the same horrors of heavy urban combat, and the defenders are proving that the ability to hold urban terrain is central to the future of operations in major interstate conflict.

“Hero City of Ukraine”

  After fifty-three days under relentless assault by Russian, Chechen, and separatist Donetsk Peoples’ Republic (DPR) forces, the outnumbered and outgunned Ukrainian defenders of Mariupol continue to contest Russian control of the city (as of 18 April 2022).  According to Dmytro Kuleba, Ukraine’s Foreign Minister, for all intents and purposes the city of 500,000 souls and Europe’s largest concentration of industrial steel production “doesn’t exist anymore”.1 Russian-led forces have employed almost every weapon system in their inventory to dislodge the tenacious Ukrainians, including Tu-22 “Linebacker” carpet bombing and even alleged chemical weapons2, but to no avail. The weeks-long relentless barrage of high explosive ordnance, street-to-street and house-to-house combat is more reminiscent of the great urban battles of the Eastern Front during the Second World War.  The parallels are so compelling that Mariupol was awarded “Hero City of Ukraine” status by President Volodymyr Zelensky3 – elevating this mid-size steel town to the plinth of the legendary Soviet Hero Cities of Smolensk, Kiev, and Stalingrad.

Indeed, the Ukrainian defense of Mariupol, and the return of interstate conflict to continental Europe is a dynamic completely unknown since May 1945. The charred hulks of Russian armored vehicles, the abandoned corpses of civilians in the streets, the leveling of entire city blocks was something that Europe – even during the height of the Cold War – had been able to avoid.  That has now changed. The Siege of Mariupol, along with the Russo-Ukrainian War more broadly, signals less of a paradigm shift in warfare, than a return to the operational approaches of the Second World War.  The West must be prepared to re-learn the operational centrality that deliberate strongpoint defense of major urban terrain will play in future LSCO scenarios in both Europe and Asia. 

The Strongpoint Defense: “The Fortress of the Azov”

As Mariupol’s defensive perimeter slowly retracted under Russian assault, elements of Ukraine’s 36th Marine Brigade, a Ukrainian Army separate motorized brigade, and Ukrainian National Guard (NGU) gendarmerie coalesced around the core of the Azov Battalion – a militia originally founded by far-right members of the Pan-East Slavic Pravyi Sektor at the outbreak the War in the Donbas (2014)4 – fortified deep within the ruins of the Azovstal Metallurgical Plant in the southeastern quadrant of the city. Here, despite the relentless pressure of Russian forces, this battalion-plus sized battlegroup has successfully established the first major urban “strongpoint” area defense since the Second World War.

In doing so, this battlegroup has successfully reduced its defended frontage, while holding the most valuable and defensible terrain within the ruins of Mariupol. Despite nearly two months of heavy fighting, and the obliteration of much of Mariupol’s infrastructure, the Ukrainian defenders holed up at Azovstal are still denying the Kremlin’s operational objectives. Every day that the Ukrainian defenders hold on to Azovstal further saps Russian and proxy moral and taxes their logistics train, it prevents Mariupol’s port and rail facilities from being used to support Russian offensive operations in the Donbas, and it continues to tie down a considerable proportion of Russia’s Southern Military District’s most capable and motivated combat formations – including the Naval Infantry of the Black Sea Fleet.

Although a positional, defensive approach executed from relative weakness, the classic “strongpoint” defense originally evolved from German experiences defending against large-scale Soviet mechanized attacks on the Eastern Front.5 Simply put, in the vast expanses of the Pontic Steppe, with off-road maneuver heavily limited by underdeveloped road networks and climatic conditions like the bi-annual Raputitsa rainy seasons, it becomes necessary to only hold a limited amount of positions in strength to maintain the defensibility of the entire front. That key terrain central to the operating of lines of communication, such as major rail crossings and port facilities can then be held in a more concentrated and defensible manner.  Without the vast resources necessary to maintain a linear defense-in-depth, an infantry formation can disrupt much larger mechanized enemy formations for much longer periods of time. Although susceptible to encirclement, as happened with Mariupol, the strongpoint defense carried out at Azovstal is proving every bit as effective as the most serious German attempts on the Eastern Front. 

Founded in 1933 and now owned by Ukraine’s largest company Metinvest, the Azovstal complex is what one DPR commander recently termed a “fortress within a city”.6  Covering nearly 12 square kilometers, the complex used to produce up to 15 million tons of iron and steel products per year.7  The site is riddled with massive blast furnaces, hundreds of buildings, and honeycombed by kilometers of underground access tunnels – all of which are heavily engineered to support the steel-forging industry.  The site lies on elevated ground surrounded on three sides by the Tahanroska Gulf to the South and the Kalmius River to the North and West. As additional standoff from the rest of Mariupol, the flood plain of the Kalmius extends Azovstal’s perimeter up to a further 600m deep of marshland along its northern flank. Along the entirety of the site’s western and southern approaches, already shielded by the Kalmius and Tahanroska respectively, lay further water obstacles including marshlands and runoff lakes of up to 600m (south) and a deep-water barge loch 250m wide (west).

Thus, the only viable avenue of approach for assaulting forces lies to the northeast. However, this sector is only marginally weaker in natural and manmade defensive terrain. This avenue naturally canalizes between the Kalmius and Tahanroska as you approach Azovstal. This canalization is further complicated by the dense residential district of Livoberezhnyi that sits outside the eastern edge of the complex. Hundreds of apartment blocks in this district will break up any attempt to assault the eastern flank of Azovstal, itself faced with a recessed railbed serving as a dry moat and backed by the heavy factory buildings of the main smelting facilities.  Andriy Biletskiy, the Azov Batallion’s first commander and former Far-Right Ukrainian parliamentarian, has aptly named the Azovstal complex “the fortress of the Azov”.8

Clausewitz’s “Stronger Form”

Estimates seem to suggest that, given the golden ratio of a minimum of 3:1 in assaulting a prepared defense, the estimated 3,500 Ukrainian defenders in Mariupol were roughly equaled to the 14,000 Russian and proxy forces when the siege began.9  Despite nearly two months of attrition, Ukrainian forces now consolidated at Azovstal are thought to number between 500 and 800.10  This means that even if Russian forces simply seek to isolate the defenders of the Fortress of the Azov, they would need a sizable amount of combat power to guard rear area operations as the Russians seek to support their planned offensive in the Donbas from the ruins of Mariupol.

Although it is likely that last defenders of Mariupol, fortified in the twisted steel and concrete of the Azovstal complex, will eventually end their resistance – through flight, surrender or death – valuable lessons are being re-learned by the West about the enduring strength of strongpoint defense of urban terrain during modern LSCO.  Whether in defense of Europe or in defense of the Western Pacific against the aggression of autocratic states, the West must be ready to re-discover the stronger form of war.

The defense of Mariupol and its strongpoint at Azovstal, whether indefinite or not, proves the validity of Carl von Clausewitz’s famous maxim that the “defensive form…is the stronger form” of war.11 While suffering loses in personnel, equipment, and time while reducing a textbook strongpoint defense might be less relevant to a motivated adversary that has outsized advantages in manpower and material, the opposite may also be true for a force that by all accounts looks highly demoralized at present.12  As Clausewitz further opined, “the weaker the motives to action are, the more will those motives be absorbed and neutralized by this difference between attack and defense, the more frequently, therefore, will action in warfare be stopped, as indeed experience teaches.”13

MAJ Viktor Stoll 

Major Viktor Stoll (US Army) has served in a variety of strategist, planner, and intelligence roles in the USINDOPACOM, USAFRICOM, and USEUCOM theaters.  He earned his MA in Modern History from King's College London and is currently pursuing his PhD in History at the University of Cambridge where he studies the nexus of Great Power Competition, colonial administration, and social scientific expertise during the Interwar Period.


1. Dmytro Kuleba, “Face the Nation Interview”, CBS News, 17 April 2022, 

2. David Axe, “Russian Bombers Just Carpet-Bombed Mariupol”, Forbes, 15 April 2022,; Ban Sabbagh, “Did Russia really use chemical weapons in Ukraine? Experts are Sceptical”, The Guardian, 12 April 2022,

3. News Desk, “Zelensky gives the honorary title ‘Hero City’ to Kharkiv, Chernihiv, Mariupol, Kherson, Hostomel, and Volnovakha”, The Kyiv Independent, 18 April 2022,

4. Roman Goncharenko, “The Azov Battalion: Extremists Defending Mariupol”, Deutsche Welle, 16 March 2022,

5. Timothy A. Wray, “Standing Fast: German Defensive Doctrine on the Russian Front During World War II”, Research Survey No. 5 (Ft. Leavenworth, KS: Combat Studies Institute, 1986), 68-108.

6. Natalia Zinets, “Ukrainians hang on at Mariupol steel plant”, Reuters, 15 April 2022,


8. Natalia Zinets, “Ukrainians hang on at Mariupol steel plant”, Reuters, 15 April 2022,

9. Anonymous, “Hundreds of Thousands face Catastrophe in Mariupol”, The Economist, 21 March 2022,

10. Anonymous, “Mariupol Defenders will Fight to the End says PM”, BBC, 18 April 2022,

11. Carl von Clausewitz, On War, translated by Col. J.J. Graham (London: Kegan Paul, Trench Trubner & Co., Ltd., 1918), I, xxvii.

12. Kris Osborn, “What’s Behind the Russian Military’s Morale Problems?”, The National Interest, 09 March 2022, 

13. Clausewitz, On War, I, 18.

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