The Siege of Sevastopol from October 1941-July 1942 is modern and was in the same country, and you are comparing Mariupol to the Alamo, which as you note was practically a skirmish in comparison? The Soviet Coastal Army and Black Sea Fleet resisted a quarter of a million Wehrmacht and Romanian troops with almost a thousand aircraft and the heaviest artillery pieces ever used in warfare, in the process losing over 300,000 casualties and almost the whole Black Sea Fleet. The entire city was destroyed. After the war Sevastopol was designated a Hero City of the Soviet Union, and in 2000 Vladimir Putin laid a wreath there to honor the defenders.

That is a much better analogy.