First Chechen war aka the meat grinder. The first Chechen war would inflict Russia its first defeat since the fall of the Soviet Union.
This conflict would also shatter the reputation of the Russian armed forces: Conscripts sent to the front straight from basic training, inept leadership, lack of all-weather/night capable helicopters and planes, tank crews trained on T-72 sent to the front in T-80, which was completely different, with a different set of strengths and weaknesses and required different handling/tactics…
More than anything else, the Russian army, trained for large scale mechanised warfare against a peer enemy, completely lacked the tactics and skills necessary to tackle an insurgency, especially in urban settings… In Chechnya, they were faced with a determined adversary, men who had served in the Red Army, too, and therefore knew their enemy’s tactics and doctrine…
The conflict resulted in complete humiliation for Moscow and a de-facto independence for Chechnya which became a threat for the surrounding Russian republics: The main source of income for Chechnya in the 1990’s was ransom, kidnapping, contraband and extortion.
It would take Moscow another president, another army staff, new tactics and another war to bring the breakaway republic back to heel. All that followed by another 10 years of counter-insurgency. It would also take Moscow almost 20 years and yet another conflict to start the reforms necessary to finally modernise its armed forces.