Aiden Aslin, a British man fighting in Ukraine, spent weeks defending the besieged city of Mariupol from Russia’s advances, as battles raged block by block for control of the strategic port. As Aslin’s unit — Ukraine’s 36th Marine Brigade — ran out of food, water and ammunition, he called his friend Brennan Phillips. “The first thing he said was, ‘I’m surrendering to the Russians,’” Phillips, a 36-year-old American, told The Washington Post of their call early Tuesday local time. Aslin said his commander was planning to surrender the unit within hours. And when Russian forces came for him, Aslin said he would “destroy his phone and dump it in the toilet,” Phillips said. They knew it could be their last call. After they hung up, Aslin sent him a message. “The last thing he said to me was, ‘Please don’t let them forget about me,’” Phillips said. Phillips hasn’t heard from him since. The Washington Post was unable to reach Aslin. In the days after Russia’s invasion, Ukraine sought volunteers to fight from all over the world. Some heeded the call, despite the risks. But Aslin joined the Ukrainian marines long before the war — in 2018, according to Phillips — following a three-year stint fighting the Islamic State alongside Syrian Kurdish forces. That’s where he met Phillips, who set up a team of combat medics in Syria and trained Kurdish and Western volunteers on the ground. Aslin then sought to defend the Donbas, a contested region in eastern Ukraine, from pro-Russian separatists seeking more territory there. Aslin settled into a life in Ukraine. He got engaged. But everything changed on Feb. 24, when Russian forces invaded. Aslin soon became part of Ukraine’s last line of defense in Mariupol, one that Ukrainian President Volodymyr Zelensky recently described as crucial in preventing Russian forces from gaining a stronger foothold in the east. “Mariupol is the heart of this war today,” Zelensky said in an interview with the Associated Press on Sunday. “It beats, we fight, we are strong. If it stops beating, we will have weaker positions.” Inside the terror at Mariupol’s bombed theater: ‘I heard screams constantly’ Aslin’s unusual story provides a window into the desperate situation in Mariupol, which has reportedly been destroyed after a blockade left it cut off from food, water, heat and humanitarian aid for over a month. Constant Russian bombardment made civilian evacuations difficult. The mayor of Mariupol, Vadym Boychenko, said Wednesday that 50,000 to 70,000 people remain in and around the city. He previously said more than 10,000 civilians have been killed. For weeks, Aslin talked of his “frustration” that Russian forces appeared not to be targeting his unit and others defending Mariupol, but rather “just targeting civilians,” Phillips said. Officials have said Russian forces were behind attacks against a maternity hospital and a theater in Mariupol that left several dead and dozens injured. Witnesses told The Post that Mariupol residents were forcefully deported to Russian-held territory. Russia stands accused of committing war crimes in Mariupol, and in other parts of Ukraine. Russia’s deliberate attacks on civilians in Mariupol are ‘war crimes,’ OSCE says Phillips said that when they spoke, Aslin seemed “in good spirits” and like he had “thought about this for quite some time.” Aslin’s unit, a day earlier, warned that it was heading into battle with dwindling supplies. The renewed attention on Mariupol comes as Russia has pared down the ambitions of its military operation in Ukraine, withdrawing forces from around the capital, Kyiv, and laying the groundwork for a major offensive in the east, according to U.S. intelligence. In a Facebook post, members of the 36th Marine Brigade said their unit had defended Mariupol for 47 days, but without supplies, they faced death or captivity. Phillips said he told Aslin: “You have to find some way out. Don’t surrender.” But Aslin, according to Phillips, said “We don’t have a choice, [we’re] completely surrounded, we have no ammunition, we have no food, we have no water, no ability to resupply.” Aslin expressed the hope that he would be freed as part of a prisoner swap between Russia and Ukraine. Russia’s Ministry of Defense said Wednesday that 1,026 members of the 36th Marine Brigade, “voluntarily laid down their arms and surrendered” near the Ilyich Iron and Steel Works north of the city. The ministry said 151 of them were wounded and treated on the spot, then later taken to a hospital in Mariupol. The group included 162 officers and 47 female fighters, the ministry said. A spokesperson for Ukraine’s Defense Ministry said Wednesday he had no information on the unit’s surrender. Aslin’s mother, Ang Wood, told the BBC that her son’s unit surrendered because they had “no weapons left to fight.” “I love my son, he is my hero — they put up one hell of a fight,” she told the BBC. Ukraine braces for new offensive as Russia reinforces military in east Aslin stood out to Phillips when they met in Syria because he had “a heart for people.” A former caretaker to elderly and disabled people turned volunteer fighter, Aslin was “one of those people that … was there for the right reasons,” says Phillips. He “took care of civilians while he was in Syria” and wanted to help end the war there. He had just extended his contract with the Ukrainian military for six more months, Phillips said, when the invasion began. Phillips posted a video on social media after his call with Aslin to draw attention to his friend’s story, he said. “I realized that anything that happens to him after this is a documented war crime,” Phillips said, citing the Geneva Conventions, which state that “prisoners of war must at all times be humanely treated.” Now, Phillips says he believes his friend is “either in Russian custody, he’s murdered, or worse.”