The greatest challenge to Russian President Vladimir Putin in his more than two decades in power has fizzled out after the rebellious mercenary commander who ordered his troops to march on Moscow agreed to go into exile and sounded the retreat. The brief revolt exposed vulnerabilities among Russian government forces, with Wagner Group soldiers able to move with armored vehicles into the Russian city of Rostov-on-Don and advance toward Moscow. Under the deal announced Saturday by the Kremlin, Wagner Group’s leader will go to neighboring Belarus, which has supported Russia’s invasion of Ukraine. Charges against him of mounting an armed rebellion will be dropped, and the Russian government said it would not prosecute Wagner fighters who took part.