U.S. President George W. Bush chose a Marine base in southern California _ one with one of the highest casualty rates in Iraq of any U.S. military base or installation _ to thank American troops fighting Iraqi insurgents. Bush was to deliver a speech on Iraq and have lunch with troops Tuesday at Camp Pendleton, 60 kilometers (38 miles) north of San Diego. More than 21,000 Marines serving in Iraq and neighboring nations are part of the 1st Marine expeditionary Force based there. "The president, first and foremost, will thank the members of our military, men and women, who have served and sacrificed to make the world a safer and better place," White House press secretary Scott McClellan said Monday. "He will also thank their families for the tremendous sacrifices that they make."