STORY: Danylo was one of the last Ukrainian defenders of Sievierodonetsk until he withdrew in a boat under the cover of night - bitter to be leaving after withstanding weeks of Russian attacks.The onslaught destroyed the city, but he says he left feeling relieved to be alive, as he and his comrades moved to higher ground."We crossed the river by boats, it was mostly under darkness for safety. The locations of the crossings were constantly changed because they were also shelled, but in general it was comfortable and even fun. // It was a shame of course because a lot of effort was put into defending it - it went on for months. But the decision was taken, so we were not too upset as we also want to live.”Both sides say Russian forces fully occupied the frontline eastern city on Saturday.Confirming Kyiv's biggest battlefield setback for more than a month following some of the war's bloodiest fighting.Another soldier, Anton, told Reuters on Sunday that defenders were ordered to pull back because, due to heavy losses, there was no point in holding on. But he believes Russian forces had been hit much harder.By then, he and Danylo were 35 miles away in Sloviansk - now one of Ukraine's key strongholds for its defense of the industrial Donbas heartland that Russia's assault is focused on capturing.“The situation in Sievierodonetsk was rather difficult, but our fellow servicemen, our boys courageously defended every house and every street. We were fighting for them, we were defending them, but we received an instruction to withdraw. // There were a lot of civilians, soldiers and everything was moving towards us being encircled.”Anton added that troops feared a rerun of the encirclement of the Azovstal steel works in the southern port city of Mariupol.Hundreds of Ukrainian fighters holed up there before eventually surrendering.Moscow denies targeting civilians in what it calls a "special military operation" in Ukraine, but Kyiv and the West have accused Russian forces of war crimes. The conflict has killed thousands and sent millions fleeing abroad.