ANDREWS AIR FORCE BASE, Md. — President Barack Obama said Monday that the meaning of Memorial Day is found in the story of ordinary Americans who become extraordinary for one simple reason: love of country. Obama, speaking to dozens of troops at Andrews Air Force Base outside Washington after his Land of Lincoln tribute in Illinois was washed out by a storm, said the nation's fallen heroes had such a deep love of country that they willingly sacrificed their own lives to protect it. "In this time of war, we pay special tribute to the thousands of Americans who have given their lives during the wars in Afghanistan and Iraq and who have earned their place among the greatest of generations," Obama said in the Monday evening speech. Vice President Joe Biden earlier made the more traditional appearance at Arlington National Cemetery on Obama's behalf, saying the country has "a sacred obligation" to make sure its servicemen and women are the best equipped and best-supported troops.