Ukrainian underground fighters highlight benefits – and long history – of wartime tunnels

Faced with the prospect of sending Russian troops into underground combat, Vladimir Putin balked. “There is no need to climb into these catacombs and crawl underground,” he told his defense minister on April 21, 2022, ordering him to call off the planned storming of a steelworks in the besieged Ukrainian port city of Mariupol.

While Putin’s backup plan – to form a seal around the trapped Ukrainian forces and wait – is no less brutal and there are reports that the Russians may still have mounted an offensive at the site, the Putin’s reluctance to send his forces into a sprawling network of tunnels beneath the complex hints at a truth in warfare: tunnels can be an effective tool in resisting an oppressor.

Indeed, since the start of the war in February, there have been reports of Ukrainian defenders using networks of underground tunnels in an effort to deny Russian invaders control of major cities, as well as provide refuge for civilians.

As an expert in military history and theory, I know there is good thinking behind the use of tunnels as a defensive and offensive tactic. Such networks allow small units to move undetected by aerial sensors and emerge in unexpected places to launch surprise attacks and then disappear. For an invader who does not have a detailed map of the underground passages, this can present a nightmare scenario, resulting in massive personnel losses, a drop in morale and an inability to complete the conquest of their urban objective – all factors that could have be taken into account by Putin. decision not to send clandestine troops to Mariupol.

A history of military tunnels from ancient roots

The use of tunnels and underground chambers in times of conflict is nothing new.

The use of tunnels has been a common aspect of warfare for millennia. Old siege forces used tunneling operations as a means of weakening otherwise well-fortified positions. This usually required engineers to build long passages under walls or other obstacles. The collapse of the tunnel weakened the fortification. If appropriate, an assault conducted immediately after the breach could lead to a successful assault of the defended position.

One of the earliest examples of this technique is depicted on Assyrian sculptures thousands of years old. As some attackers climb ladders to storm the walls of an Egyptian city, others can be seen digging into the foundations of the walls.

Assyrian engraving of the siege of an Egyptian fort.
The Trustees of the British Museum, CC BY-SA

Roman armies relied heavily on sophisticated engineering techniques such as placing arches in the tunnels they built during sieges. Roman defenders also perfected the art of digging counter-tunnels to intercept those used by attackers before they presented a threat. Upon entering an enemy tunnel, they flooded it with caustic smoke to chase the enemy away or launched a surprise attack on unsuspecting miners.

The success of tunnels under fortifications led medieval European engineers to devise ways to thwart the tactic. They built castles on rock foundations, making any attempt to dig beneath them much slower, and surrounded walls with moats so the tunnels needed to be much deeper.

Although tunneling remained an important aspect of sieges in the 13th century, it was eventually superseded by the introduction of gunpowder artillery, which proved a more effective means of breaching fortifications.

However, in the mid-19th century, advances in mining and tunneling led to a resurgence of underground approaches to warfare.

During the Crimean War in the 1850s, British and French attackers attempted to tunnel under Russian fortifications in the Battle of Sevastopol. Ten years later, Ulysses S. Grant authorized an attempted tunnel under Confederate defenses during the Siege of Petersburg, Virginia. In both cases, large caches of gunpowder were placed in chambers created by tunnels under key positions and detonated in coordination with an infantry assault.

Tunneling in the Age of Air Power

With war increasingly relying on aircraft in the 20th century, military strategists again turned to tunnels – undetectable from the sky and protected from falling bombs.

The black-and-white photo shows two World War I soldiers listening to a device while seated in a tunnel.
Listening under enemy lines during the First World War.
adoc-photos/Corbis via Getty Images)

During World War I, tunneling was attempted as a means of launching surprise attacks on the Western Front, potentially bypassing the trench system on the other side and remaining undetected by aerial observers. In particular, the Ypres Salient in war-torn Belgium was the site of hundreds of tunnels dug by British and German miners, and the horrific stories of fighting underground provide one of the most terrifying vignettes. of this terrible war.

During World War II, Japanese troops in occupied areas of the Pacific built extensive networks of tunnels to render their forces virtually immune to air attack and naval bombardment from Allied forces. During amphibious assaults in places like the Philippines and Iwo Jima, American and allied forces faced a maze of Japanese tunnel networks. Eventually, they resorted to high explosives to collapse the entrances to the tunnels, trapping thousands of Japanese soldiers inside.

The Viet Cong tunnel networks, particularly around Saigon, were a vital part of their guerrilla warfare strategy and remain a popular tourist stop today. Some of the tunnels were large enough to house hospitals and barracks and strong enough to withstand anything short of nuclear bombardment.

A drawing depicts men and women crawling along a tunnel structure in Vietnam
Diagram of a typical tunnel structure in Cu-Chi, Vietnam.
Didier Noirot/Gamma-Rapho via Getty Images

The tunnels not only protected Vietnamese fighters from overwhelming American air power, they also facilitated hit-and-run type attacks. Specialized “tunnel rats”, American soldiers who ventured into the tunnels armed only with a knife and a pistol, became adept at navigating the tunnel networks. But they could not be trained in sufficient numbers to negate the value of the tunnel systems.

Tunnels for terrorism

In the 21st century, tunnels have been used to facilitate the activities of terrorist organizations. During the US invasion of Afghanistan, military operatives soon discovered that al-Qaeda had fortified a series of tunnel networks connecting natural caves in the Tora Bora region.

Not only did they conceal the movement of troops and supplies, but they were impervious to virtually every weapon in the US-led coalition’s arsenal. The compounds included air filtration systems to prevent chemical contamination, as well as massive warehouses and sophisticated communications equipment allowing al-Qaeda leaders to keep control over their followers.

And tunneling activity in and around Gaza continues to provide a tool for Hamas to bring fighters into Israeli territory, while allowing Palestinians to circumvent Israel’s blockade of Gaza’s borders.

Soviet tunnels and Ukraine

Many of the tunnels used today in Ukrainian efforts to defend the country were built during the Cold War era, when the United States conducted regular overflights of Soviet territory.

To counter the significant air and satellite advantage held by the United States and NATO, the Soviet military dug underground passages under major population centers.

These underground systems provided some shelter for the civilian population in the event of a nuclear attack and allowed the movement of military forces unobserved by the ubiquitous eyes in the sky.

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These same tunnels serve to connect much of Mariupol’s industrial infrastructure today – and have become a major asset to the outnumbered Ukrainian forces.

Other Ukrainian cities have similar systems, some dating back centuries. For example, Odessa, another key Black Sea port, has a network of catacombs that stretches over 2,500 kilometers. It began as part of a limestone mining effort – and to date there is no documented map of the full extent of the tunnels.

In the event of a Russian assault on Odessa, local knowledge of the dungeons could prove extremely valuable to the defenders. The fact that more than 1,000 entrances to the catacombs have been identified should surely give Russian attackers pause before launching any attack on the city – just as the tunnels under a steelworks in Mariupol forced Putin to rethink his plans to storm installation.

Bonny J. Streater