MARJAH, Afghanistan – Marines and Afghan troops cleared the last major pocket of resistance in the former Taliban-ruled town of Marjah on Saturday — part of an offensive that is the run-up to a larger showdown this year in the most strategic part of Afghanistan's dangerous south. Although Marines say their work in Marjah isn't done, Afghans are bracing for a bigger, more comprehensive assault in neighboring Kandahar province, the birthplace of the Taliban where officials are talking to aid organizations about how to handle up to 10,000 people who could be displaced by fighting. "I was in Kabul, and we were talking that Kandahar will be next, but we don't know when," said...