STORY: Ukraine's military ceded control of the strategic port city of Mariupol to Russia on Tuesday, announcing it was working to evacuate all remaining troops from their last stronghold in the Azovstal steel plant. Ukraine President Volodymyr Zelenskiy stressed the importance of saving lives in his nightly address.“We hope we’ll be able to save the lives of our guys. There are severely wounded ones among them. They are given care. I want to stress that Ukraine needs Ukrainian heroes alive. That's our principle.”Reuters saw at least five buses arrive in the Russian-controlled city of Novoazovsk, to the east of Mariupol, late on Monday.The buses were seen marked with the Russian pro-war symbol Z.They arrived with heavily wounded Ukrainian troops from Azovstal.Ukraine’s military said in a statement it had ordered its commanders at the steelworks to save the lives of the defenders, saying, “The ‘Mariupol’ garrison has fulfilled its combat mission."53 heavily wounded defenders were sent to Novoazovsk, while some 200 others were taken to another town, north of Mariupol, said Ukraine’s deputy defense minister, Anna Malyar.She confirmed the evacuations were part of a potential prisoner exchange with Moscow. The evacuations likely mark the end of the longest and bloodiest battle of Russia’s war in Ukraine and a significant defeat for Ukraine.There’s been no immediate response from Moscow to the developments in Azovstal. Mariupol is now in ruins after a Russian siege that Ukraine says killed tens of thousands of people in the city.Since Russia launched what it calls a “special military operation” in February, the port city’s devastation has become a symbol - both of Ukraine's resistance, and of Russia's willingness to devastate Ukrainian cities that hold out.