Hundreds of die-hard Ukrainian soldiers who had made a last stand against Russian forces from a Mariupol steel mill faced an uncertain future Tuesday under Kremlin custody after Ukraine’s military ordered them to surrender.

The surrender directive, issued late Monday, made the soldiers prisoners and ended the most protracted battle so far of the nearly 3-month-old Russian invasion of Ukraine.

Even as Russia has struggled on other battlefronts, the surrender at Mariupol solidified one of Russia’s few significant territorial achievements — the conquest of a once-thriving southeast port. The surrender also gave Russia’s state-run media the ingredients for claiming its side was winning.