It’s worth bringing up the case of the Chechen war, where Russia eventually prevailed, but at enormous human cost of to all sides and, as usual, civilians.
Though literally nothing about this war makes a lick of strategic sense for Russia.
see "Natural gas transmission system of Ukraine" https://en.wikipedia.org/wiki/Natural_gas_transmission_syste...
the discussion about Norstream2 and to a lesser extent NATO membership: Since Russia is an oligarchy its "sense" is defined by Putin's ego such as "reuniting Russia" again as it was and ruling it as its Tsar.