WASHINGTON (May 25, 2015) -- President Barack Obama used the stories of three Soldiers, who died in Afghanistan, to illustrate the values of the thousands of Service members, who have made the ultimate sacrifice in the nation's wars.

Joined by Defense Secretary Ash Carter and Army Gen. Martin E. Dempsey, chairman of the Joint Chiefs of Staff, Obama spoke at Arlington National Cemetery's amphitheater after laying a wreath at the Tomb of the Unknown Soldier in observance of Memorial Day.

Army Spc. Wyatt Martin and Army Sgt. 1st Class Ramon Morris were 15 years apart in age and traveled different paths in life, the president said, but their paths took them to the same unit in Afghanistan and made them brothers in arms.

"In December, an [improvised explosive device] struck their vehicle. They were the last two Americans to give their lives during our combat mission in Afghanistan," Obama said. "These two men, these two heroes, if you saw them passing on the street, you wouldn't have known they were brothers. But under this flag, in common cause, they were bonded together to secure our liberty, to keep us safe."

Like Martin and Morris, Army Cpl. John Dawson shared the same passion and convictions about serving his country, Obama said.

"In April, an attacker wearing an Afghan uniform, fired at a group of American Soldiers," the president said. "And Dawson became the first American Service member to give his life to this new mission to train Afghan forces. The words on John's dog tag were those of scripture: 'Greater love has no other than this, than to lay down your life for your friends.'"

RECOGNIZING 147 YEARS OF TRIBUTE

Americans have set aside Memorial Day for 147 years to pay solemn tribute to brave patriots, who gave their "last full measure of devotion" for the nation, Obama said. "While the nature of war has changed over that time," he added, "the values that drive our brave men and women in uniform remain constant: honor, courage, selflessness."

The nation's patriots have ranged from those who sparked the American Revolution, those who saved a union and those who defeated tyranny in Europe and the Pacific, he said. Americans also braved the mountains of Korea, the jungles of Vietnam and the deserts of the Middle East, and became the men and women of the 9/11 generation, he said.

"This year, we mark a historic anniversary: 70 years since our victory in World War II," Obama said. "More than 16 million Americans left everything they knew to fight for our freedom. More than 400,000 gave their lives."

The president asked World War II heroes, their Families and friends of the fallen to stand "so our country can thank you once more," he said.

FREEDOMS OFTEN TAKEN FOR GRANTED

Most Americans do not fully understand the sacrifice that 1 percent of the population makes by serving in the all-volunteer armed forces - one that "preserves the freedoms we too often take for granted," the president said.

"Few know what it's like to take a bullet for a buddy, or to live with the fact that he or she took one for you, he said. "But our Gold Star Families, our military Families, our veterans - they know this intimately.

"Whenever I meet with our Gold Star Families, … I hear their pride through their tears as they flip through old photos and run their fingers over shiny medals, Obama continued. "I see that their hearts are still broken, and yet still full of love. They do not ask for awards or honors. They do not ask for special treatment. They are unfailingly humble. In the face of unspeakable loss, they represent the best of who we are."

FALLEN BELONG TO NATION

The sons and daughters and brothers and sisters, who lay down their lives for American freedom belong to all U.S. citizens, the president said.

"We benefit from their light, their positive influence on the world," he said. "And it's our duty -- our eternal obligation - to be there for them too, to make sure our troops always have what they need to carry out the mission, to make sure we care for all those who have served, to make sure we honor all those whom we've lost, to make sure we keep faith with our military Families, to make sure we never stop searching for those, who are missing or trying to bring home our prisoners of war. And we are grateful for the Families of our [prisoners of war and those missing in action]."

REFLECTION OF AMERICA

The hallowed ground of Arlington National Cemetery is more than the final resting place of heroes, Obama said, adding that it also is a reflection of America.

"It's a reflection of our history - the wars we've waged for democracy, the peace we've laid to preserve it," Obama said. "It's a reflection of our diversity - men and women of all backgrounds, all races and creeds and circumstances and faiths, willing to defend and die for the ideals that bind us as one nation.

"It's a reflection of our character," he continued, "seen not only in those who are buried here, but also in the caretakers, who watch over them and preserve this sacred place and in the sentinels of the 3rd Infantry Regiment, who dutifully, unfailingly, watch over those patriots known only to God, but never forgotten."

COST OF NATION'S BLESSINGS

The nation endures because of the Americans, who rest beneath Arlington's beautiful hills and in sacred ground across the country and around the world, the president said.

"Each simple stone marker, arranged in perfect military precision, signifies the cost of our blessings," Obama said. "It is a debt we can never fully repay, but it is a debt we will never stop trying to fully repay."

The president urged Americans to be a nation worthy of their sacrifice - "living our own lives the way the fallen lived theirs [as] a testament that 'greater love has no other than this, than to lay down your life for your friends.'"

Though this year is the first Memorial Day since the end of U.S. combat operations in Afghanistan, the president said, "we are acutely aware, as we speak, our men and women in uniform still stand watch and still serve, and still sacrifice around the world."

Several years ago, the nation had more than 100,000 troops in Afghanistan, and today fewer than 10,000 troops remain to train and assist Afghan forces, he said.

"We'll continue to bring them home and reduce our forces further, down to an embassy presence by the end of next year," Obama said. "But Afghanistan remains a very dangerous place. As so many Families know, our troops continue to risk their lives for us."