Its almost as if the Russian military is dated, demoralized, didnt want to go in the first place, is invading someone elses land which is largely open with no cover, didnt actually prepare or equip its soldiers for the type of enemy it would be facing, with the invaded forces being much more highly motivated and equiped as well as prepared for exactly what Russia threw at them.
These high numbers make sense when you stop and look at how utterly ill prepared Russia was and well prepared Ukraine was. Russia is essentially running across the largest no mans land imaginable. Remember in WW1 where you still had some idiots acting like this was the old warfar so had shit like calvalry and ignoring trenches? That's Russia right now.
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How do you expect tanks to capture and hold territory when modern weapons can allow infantry to much more easily deal with tanks? How do you expect tanks to deal with major population centers? Unless you think that Russia is just going to level entire cities to ensure no one can live there at all. In which case its not capturing, its scorched earth.
You're looking at tanks from the technological standard of decades ago. Your knights are no longer imprenetrable. The big counter to a tank is no longer another tank.