Mutinous Russian mercenary fighters barrelled towards Moscow on Saturday after seizing a southern city overnight, with Russia's military firing on them from the air but seemingly incapable of slowing their lightning advance. Facing the first serious challenge to his grip on power of his 23-year rule, President Vladimir Putin vowed to crush an armed mutiny he compared to Russia's Civil War a century ago. 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...