Man, I was sure when he was pushing for Moscow shooting down MOD copters, and just motoring, he was actually gonna fucking do it. The man was a monster but he could have etched his place in history taking down a bigger threat to the world, and ending Putin once and for all, he had the momentum caught them off guard, and was seriously making a run at it, then he just fucking quit. I think my heart broke a little bit.
If he had pushed harder and recruited along the way with huge sign up bonuses he may have been somewhat successful. He probably could have taken Moscow... but then he would eventually have to endure a siege after that, which he definitely wouldn't have won.
You don't need to take the whole city, just Putin. And he didn't have many defenses. Russia is very apathetic to who is in charge, they have been trained to uncritically support whoever looks like they're in charge.