(CBS News) -- Two days before Memorial Day weekend festivities officially kicked off, a cluster of war veterans donning lime green "Honor Flight" T-shirts filed down a narrow pathway at Arlington National Cemetery toward the Tomb of the Unknown Soldier.
A supervisor whispered instructions to a group of students heading back from watching the changing of the guard: "Make sure to shake their hands and thank them." The students, as they passed, dutifully shook each hand, save for those at the helm of their fellow heroes' wheelchairs. "Thank you for your service," some said, and the veterans - donning various ribbons and insignia on their caps and sporting on their shirt-backs the names of their respective wars - reciprocated with big smiles and high-fives.
The veterans' trip had nothing to do with Memorial Day; the non-profit Honor Flight Network schedules tours virtually year-round, to give them a chance to visit their memorials. And in fact, Memorial Day, by definition, is a federal holiday set aside to acknowledge exclusively the servicemen and women who have fallen in the line of duty - not to be confused with Veterans Day, which honors all members, both living and dead, who served with the United States military.
Still, longstanding traditions on the last Monday of May and the days leading up to it propel to the forefront of a nation's conscious acts of sacrifice and honor often lost at the summer's cusp among barbecues and swimming pool openings. And for acting service members, Command Sgt. Maj. Phillip Cantrell, Regimental Sgt. Major of the Old Guard's 3rd U.S. Infantry Regiment, told CBS News, the fruits of those traditions offer them "the greatest sense of pride and honor to be an American."
"Memorial Day is best described as the words inscribed on this monument," Cantrell said, standing in Arlington National Cemetery - the birthplace of Memorial Day - before the Confederate Memorial. "'Not for fame or reward; not for place or for rank; not lured by ambition or goaded by necessity; but in simple obedience to duty, as they understood it. These men suffered all, sacrificed all, dared all, and died.'"
The Confederate Memorial was built in 1901 - 36 years after the end of the Civil War and 33 after Gen. John Logan, national commander of the Grand Army of the Republic, ordered in 1868 that the tombstones of Union soldiers be decorated every May 30 as a way to remember those who had fallen in the war. Still aching from their bitter loss, and salt in the wound from the government's decision to designate Arlington - which housed the plantation of Confederate Gen. Robert E. Lee - as the war's official cemetery, Southern states ignored the holiday for decades.
After World War I, Cantrell explained, "when it was recognized there was a need to tie the two together to mend the bonds, it was determined that we would recognize all service members. In 1901 they built [the Confederate Memorial] and allowed the Confederate soldiers' families to come in and decorate the graves the same as the Union soldiers' families had."
To carry on that custom, the Old Guard, "about 40 years ago," Cantrell said, began to place American flags before the headstone of every grave in Arlington Cemetery - an annual undertaking the Thursday before Memorial Day known as "flags-in" that rolls out in five phases: Planning, preparation, execution, maintenance and recovery.
"The planning phase is done about six months out," Cantrell said, "where we start planning how we're going to break the sections up for each company, and for each soldier. Then we go into the execution phase, the day of, which is the Thursday before Memorial Day. We bring the soldiers in after the last funeral is complete at the end of the day and we place a flag one foot in front of every head stone."
Cantrell said for him, completion of the flag placement Thursday is the most touching moment of the entire weekend: "At the end of the day," he said, "when there are flags across the whole entire cemetery, you can look across to se the service and sacrifice that people of our country have made in order for us to remain a free country."
Maj. John Miller of the Old Guard told CBS News that throughout the weekend and on Memorial Day, families who visit the cemetery often "want a memento of their family member that's served," and will take the flags home. That's where the maintenance phase comes in: Throughout the weekend, members of the Old Guard patrol the grounds, ensuring flags that are taken are promptly replaced.
The Tuesday following the holiday, about 1,200 soldiers from the regiment will storm the cemetery between 4 and 6 a.m., recovering every single flag before dawn.
"It's magical," Miller said.
When Memorial Day arrives, the president will take part in a wreath-laying at the Tomb of the Unknown Soldier. Planning for the ceremony, Miller said, is extensive, with involvement from the Military District of Washington, Secret Service, Park Police and staff of Arlington National Cemetery.
"It's quite an undertaking to do any of these wreaths," he said. "The main military rehearsal [is the Thursday before], where we'll come in in the morning and do a complete run-through of having a stand-in government official - it'll probably just be one of our guys - doing a wreath with the sentinels here on the plaza. [Then on Monday], we'll run through between 5 and 7 o'clock in the morning... to make sure everything is picture perfect for the president."
Off-campus from the cemetery, weekend events include a parade in which each branch of service will be represented, and a patriotic concert on the West Lawn of the U.S. Capitol. To rally for the government's recognition and protection of Prisoners of War (POWs) and soldiers Missing in Action (MIAs), motorcyclists will join the non-profit Rolling Thunder on Sunday in riding around the National Mall. And keeping alive the poem-inspired ritual, the Veterans of Foreign Wars USA (VFW) will distribute "Buddy Poppies" for its 93rd year.
Some, though - including the VFW - have voiced concerns that the meaning of Memorial Day was lost with the Uniform Monday Holiday Act of 1971, which set federal holidays on Mondays to ensure three-day weekends. In 2002 the organization said changing the date "has contributed greatly to the general public's nonchalant observance of Memorial Day"; three years earlier, the late Sen. Daniel Inouye, D-Hawaii, introduced a now-idle bill proposing Congress restore the official observance of Memorial Day to May 30.
But it's not about what day the holiday falls on, Cantrell argued, and as political battles roil on in the Capitol and across the nation about the rights and wrongs of guns, immigration policy and the ever-foiling federal budget, Cantrell said Memorial Day "one hundred percent" offers the chance for Americans to remember what they have in common.
"I think this is a great opportunity for us to look at our country as - regardless of what our beliefs are," he said, "at the end of the day, the service members who have sacrificed their lives are here to provide us all freedom."