Dmytro Kozatski’s images, uploaded before he was captured along with up to 2,500 fighters, show soldiers — many of them seriously wounded and missing limbs — taking respite from the Russian onslaught in and around the complex.
The dimly lit pictures evoke the almost post-apocalyptic existence of the Ukrainian fighters, sheltering in the complex's tunnel system.
The steelworks, now a vast expanse of mangled and rusting metal after weeks of artillery bombardment that included thermite incendiary munitions that burn at more than 2,000°C, had become a symbol of the war’s destruction.
The massive factory, which dates back to the Second World War, once produced almost six million tonnes of steel and was the main industrial site in the city.
Mariupol has been the site of some of the heaviest fighting in the war with Russia.
Being only 60 kilometres from the Russian border, the city soon became a key prize in Russia’s offensive, presenting Moscow with the chance of a standout victory after the collapse of their efforts to take Kyiv.
Fierce bombardments hit the city with some of Russia’s most feared weapons used, including the TOS-1 multi-launch rocket system, which uses thermobaric bombs that create devastating shock waves.
Within weeks, much of the city had fallen to Russian forces. But the steelworks soon became a haven for fighters and hundreds of civilians; not only does it host a large tunnel complex, but nuclear bunkers were built under its mills during the Soviet era.
This enabled the determined defenders to turn it into their last bastion during the struggle for the city, even as hundreds of civilians were evacuated during a series of ceasefires which Russian forces were accused of breaching.