Mark MacKinnon, the Globe and Mail's China correspondent, and staff photographer John Lehmann are exploring China at a defining moment in its modern history. Travelling mainly by rail, they will roughly follow the path taken nearly 70 years ago by Mao Zedong and his beleaguered Red Army in what became known as the Long March – the legendary trek that led to the establishment of the People's Republic – to look at the challenges facing Mao's latest successor, Xi Jinping.