PHOTOS: Inside the front-line trenches around a destroyed town where Ukraine is fighting the war's longest and bloodiest battle

• Trench warfare has been a major element of fighting between Ukraine and Russia around the eastern city of Bakhmut.
• Photographs from the area show elaborate networks of trenches that slice through the earth.

Ukraine's grinding but steadfast defense of the country's eastern Donbas region is a battle in the trenches, where soldiers endure harsh conditions and the constant threat of artillery and gunfire, sometimes only a short distance away from the enemy.

Around the war-torn city of Bakhmut, where fierce fighting between Ukrainian and Russian forces has been raging for months, winding trenches shield and house Kyiv's troops along the front lines. The elaborate networks of hollowed-out earth — which both sides have used throughout the war — zig-zag and cross over themselves, sometimes proving to be a battleground for close combat.

A French photographer who documented life in Ukraine's trenches before the war previously described the fortifications in Ukraine's eastern Donbas as "endless bowels of Earth."

Here's what life looks like in the front-line trenches near Ukraine's bloodiest and most intense battle, the fight for Bakhmut.

Trenches are not a revolutionary aspect of land warfare — they are part of a tactic that's been used in many conflicts going back in history, though perhaps they are most well-known for their role during World War I.

Ukrainian servicemen make a trench near Bakhmut on February 1, 2023, amid the Russian invasion of Ukraine.      Photo by YASUYOSHI CHIBA/AFP via Getty Images

As a grinding war of attrition that features trenches, constant artillery barrages, incremental gains, human wave attacks, and extremely heavy casualties, the fighting in Ukraine has often drawn comparisons to the First World War.

Ukrainian soldiers in trenches in the frontline close to Bakhmut, Donetsk region, Ukraine, Wednesday, Feb. 8, 2023.      AP Photo/Libkos

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Ukraine's battlefields, however, have modern touches like the use of advanced drones that buzz overhead.

A Ukrainian infantryman with the 28th Brigade moves through a network of frontline trenches on March 05, 2023 outside of Bakhmut, Ukraine.      Photo by John Moore/Getty Images

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Fighting in trenches can be "brutal," Billy Fabian, a senior fellow in the defense program at the Center for New American Security and former infantry officer in the US Army, told Insider.

Ukrainian soldier of the 80th Brigade with a AK-47 in a trench in the direction of Bakhmut, 26 March 2023.      Photo by Diego Herrera Carcedo/Anadolu Agency via Getty Images

Trenches are a "survival tactic" and are constructed to protect front-line troops from machine guns and accurate artillery, rather than leave them exposed to this modern firepower out in the open, Fabian added.

Ukrainian soldiers in a trench under Russian shelling on the frontline close to Bakhmut, Donetsk region, Ukraine, Sunday, March 5, 2023.      AP Photo/Libkos

"Trench warfare often emerges because of a combination of a relatively static battlefield, where forces are in the same place for a long time, so they have the time to dig these elaborate fortifications," Fabian said.

A Ukrainian sniper with the 28th Brigade looks towards a Russian position from a frontline trench on March 05, 2023 outside of Bakhmut, Ukraine.      Photo by John Moore/Getty Images

Fabian said trenches involve the constant threat of artillery, a major attack, or a raid, and soldiers often endure really rough conditions.

Ukrainian medic "Doc" with the 28th Brigade runs through a partially dug trench along the frontline on March 05, 2023 outside of Bakhmut, Ukraine.      Photo by John Moore/Getty Images

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Conditions in the trenches can really deteriorate, Fabian said. "People living in these narrow trenches for weeks and months on end — they get dirty."

Ukrainian soldiers in a shelter in trenches in the frontline close to Bakhmut, Donetsk region, Ukraine, Wednesday, Feb. 8, 2023.      AP Photo/Libkos

Trenches can also be cold and fill up with water when it rains, leading to disease and other health issues like trench foot, a common ailment in World War I.

Ukrainian soldier in a trench near Bakhmut, March 22, 2023.      Photo by Diego Herrera Carcedo/Anadolu Agency via Getty Images

"The living conditions are very harsh and unhealthy," Gaelle Girbes, the French photographer, told Insider previously of life in Ukrainian trenches as the country fought Russian-backed separatists in the east prior to the invasion. Life "is really hard," she added, saying it takes a mental toll on the troops. Given the intensity of the battle for Bakhmut and the strains on the armed forces, the situation now may be far worse.

Ukrainian soldiers are seen in a trench on New Year's Eve in Bakhmut, Ukraine on December 31, 2022.      Photo by Diego Herrera Carcedo/Anadolu Agency via Getty Images

Fabian said fighting between Ukraine and Russia around Bakhmut — where both sides make use of trenches — comes at a "very high cost," echoing what officials and military leaders have said about the costly battle.

Ukrainian soldiers take shelter in a bunker while awaiting orders to fire a British-made L118 105mm Howitzers on Russian trenches on March 04, 2023 near Bakhmut, Ukraine.      Photo by John Moore/Getty Images

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Both sides, Russian forces, including Wagner mercenaries, and Ukrainian soldiers, are continuing to push troops to the front, pushing them into a bloody fight for a town gaining significance despite its limited strategic value. So far, here don't seem to be any major breakthroughs, where massive sections of the front are collapsing, Fabian said.

Ukrainian soldiers take shelter from Russian shelling in a trench in the direction of Bakhmut on March 22, 2023.      Photo by Diego Herrera Carcedo/Anadolu Agency via Getty Images

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Fabian described combat as slow and grinding, with "positional warfare" that features "attritional ebb and flow."

Ukrainian soldiers of the 80th brigade in a trench in the direction of Bakhmut on March 26, 2023.      Photo by Diego Herrera Carcedo/Anadolu Agency via Getty Images

When there's attritional warfare on the battlefield, Fabian says the equation boils down to who gets exhausted first.

Ukrainian soldiers of the 80th brigade in a trench in the direction of Bakhmut on March 26, 2023.      Photo by Diego Herrera Carcedo/Anadolu Agency via Getty Images

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"Does the attacker reach a culmination because they just don't have enough combat power anymore to gain anything?" Fabian asked. "Or does the defender no longer have enough people to sort of plug the breach?"

Newly made trenches are seen nearby Bakhmut frontline as war continues between Ukrainian forces and Russian troops in Nykyforivka, Donetsk Oblast of Ukraine on March 02, 2023.      Photo by Narciso Contreras/Anadolu Agency via Getty Images