Mutinous Russian mercenary fighters who surged most of the way to Moscow have agreed to turn back to avoid bloodshed, their leader said on Saturday, in a de-escalation of what had become a major challenge to President Vladimir Putin's grip on power. The fighters of the Wagner private army run by former Putin ally Yevgeny Prigozhin were already most of the way to the capital, having captured the city of Rostov and set off on an 1,100 km (680 mile) race to Moscow.