ARLINGTON, Virginia (CNN) -- Barack Obama marked his first Memorial Day as president on Monday, calling on Americans to remember U.S. troops who died in the service of their country and navigating a Civil War memorial controversy.



President Obama pays tribute to veterans at a wreath-laying at Arlington National Cemetery on Monday.



The president participated at the 141st annual Memorial Day wreath-laying ceremony at Arlington National Cemetery's Tomb of the Unknowns.



The men and women buried at Arlington "waged war so that we may know peace," Obama said.



"They were willing to give up everything for the defense of our freedom [and] were willing to sacrifice all for their country. ... They are the best of America."



Also Monday, Obama decided to continue a controversial presidential tradition of honoring Southern Civil War soldiers by sending a wreath to Arlington's Confederate Memorial, according to the White House.



But the president decided to start what may become a new tradition by sending a wreath to the African-American Civil War Memorial at Vermont Avenue and U Street Northwest in Washington.  See how fallen service members are being remembered »



Critics had called for an end to the longtime presidential practice of laying a wreath at the Confederate site. Last week, roughly five dozen professors sent a letter to Obama calling the tradition offensive to African-Americans.



Some observers recently suggested adding the recognition of the African-American memorial as a possible compromise.



Wreaths also were sent to be placed on the mast of the USS Maine and the Spanish-American War Memorial, both in Arlington National Cemetery.



Obama also hosted a White House breakfast for several military Gold Star families, the relatives of service men and women killed in action.



A separate Memorial Day observance was held at the Vietnam Veterans Memorial at 1 p.m. ET, and the National Memorial Day Parade started an hour later.



All Americans were asked to pause for a moment of remembrance at 3 p.m. local time Monday "because it is the time when most Americans are enjoying their freedoms on the national holiday," according to the White House Commission on Remembrance.



"The moment does not replace traditional Memorial Day events; rather it is an act of national unity in which all Americans, alone or with family and friends, honor those who died for our freedom," the commission said on its Web site.



"It will help to reclaim Memorial Day as the sacred and noble holiday it was meant to be. In this shared remembrance, we connect as Americans."



The 3 p.m. observances included, among other things, an interruption of Major League Baseball games and the pausing of the Washington Memorial Day Parade.



The National Grocers Association and Food Marketing Institute has asked shoppers to pause in stores across the nation.



Memorial Day was first marked May 30, 1868, three years after the end of the Civil War. Congress declared it a national holiday in 1971.



CNN's Emily Schultze contributed to this report.
Where does the President send a wreath? Where does the wreath-laying take place? Where does the President sends wreath ? What does Obama do that is controversial? At what event did Obama take part ? What did he say about the men and women? What did Obama take part of? What did Obama continue? What is Obama continuing to do ?
to the African-American Civil War Memorial Arlington National Cemetery Arlington's Confederate Memorial, honoring Southern Civil War soldiers Memorial Day "waged war so that we may know peace," president participated at the 141st annual Memorial Day wreath-laying ceremony at Arlington National Cemetery's Tomb of the Unknowns. a controversial presidential tradition of honoring Southern Civil War soldiers by sending a wreath to Arlington's Confederate Memorial, a controversial presidential tradition of honoring Southern Civil War soldiers by sending a wreath
question: Where does the President send a wreath?, answer: to the African-American Civil War Memorial | question: Where does the wreath-laying take place?, answer: Arlington National Cemetery | question: Where does the President sends wreath ?, answer: Arlington's Confederate Memorial, | question: What does Obama do that is controversial?, answer: honoring Southern Civil War soldiers | question: At what event did Obama take part ?, answer: Memorial Day | question: What did he say about the men and women?, answer: "waged war so that we may know peace," | question: What did Obama take part of?, answer: president participated at the 141st annual Memorial Day wreath-laying ceremony at Arlington National Cemetery's Tomb of the Unknowns. | question: What did Obama continue?, answer: a controversial presidential tradition of honoring Southern Civil War soldiers by sending a wreath to Arlington's Confederate Memorial, | question: What is Obama continuing to do ?, answer: a controversial presidential tradition of honoring Southern Civil War soldiers by sending a wreath