CAMP BASTION, Afghanistan - More than 100 U.S. Marines stood at attention before four empty boots and two sets of dog tags Tuesday to honor the first Marines to die in Afghanistan since their unit's deployment last month. 1st Sgt. Luke J. Mercardante, 35, and Cpl. Kyle W. Wilks, 24, died in a roadside bomb explosion in the Panjwayi district of Kandahar province on April 15, said Lt. Col. Ricky Brown, the commander of Combat Logistics Battalion 24, 24th Marine Expeditionary Unit, based at Camp Lejuene, North Carolina. Dark, overcast skies, a blustery wind and light droplets of rain reflected...