Courtesy Clemson University 'It is possible to hold opposing viewpoints and debate issues without rancor and disrespect,' Clemson University President James Barker wrote Tuesday.

The president of Clemson University reprimanded the school's football fans Tuesday for booing President Barack Obama during a military ceremony last weekend, saying there is only one president, "and he is president of us all."

The display came as students were taking their oath upon being inducted into the university's Reserve Officer Training Corps on Military Appreciation Day during Clemson's 38-17 victory over Virginia Tech at Memorial Stadium in Clemson, S.C. The booing began as the members recited their pledge to "obey the orders of the president of the United States."

The booing, first reported Sunday by the Daily Kos, drew a mixed reaction on the Clemson sports message board TigerNet. One fan called the display "disgusting," adding, "We have actually dropped into the sewer," noting that the ceremony was intended to honor "military heroes and future defenders of our freedom."

But others defended the booing. One wrote: "Even the General who was administering the oath smiled at the booing. He knows the truth."

In an e-mailed message to students Tuesday, Clemson President James Barker said many people had contacted him to "express their sadness and disappointment."

"Freedom of speech is a right which makes our country great," But he agreed that the booing was inappropriate because "this ceremony was a sacred moment to the recruits, their families, and many others in attendance."

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Booing the president at sporing events is a tradition that goes back at least as far as the administration of Herbert Hoover, who newspaper reports of the time reported was booed at the opening game of the 1931 World Series between the St. Louis Cardinals and the Philadelphia Athletics.

Obama was booed when he emerged to throw out the first pitch at Nationals Stadium in Washington in 2010:

So was President George W. Bush when he opened Nationals Stadium in 2008, their inaugural season:

First Lady Michelle Obama and Vice President Joe Biden's wife, Jill, were booed last year at a NASCAR race in Miami:

Following is Barker's full letter to Clemson students:

Dear Clemson: Saturday's football game marked Clemson's annual observance of Military Appreciation Day, a time when we pay tribute to veterans, men and women currently serving and those who gave their lives to protect us. Clemson has a strong military heritage, and this day is always a special occasion. Unfortunately, the day was marred by bad behavior from some fans. During the ceremony inducting ROTC cadets into the military, a number of fans booed during the section of the oath they take to obey the President of the United States. I understand that we are in the home stretch of a heated presidential election and that freedom of speech is a right which makes our country great. Regardless of one's political leanings, however, this ceremony was a sacred moment to the recruits, their families, and many others in attendance. Many Clemson people have contacted me to express their sadness and disappointment at this public display of disrespect for the office of the President and the young people taking a solemn oath that day. I share those sentiments. As the election draws closer, negative campaigning is intensifying on both sides. The heated rhetoric and lack of civility we hear every day on TV, radio and in social media can be contagious. But it is possible to hold opposing viewpoints and debate issues without rancor and disrespect — as demonstrated at a recent Strom Thurmond Institute roundtable discussion with political science Professors Bruce Ransom and Dave Woodard. Political campaigns seek to divide us — to highlight differences in order to drive us into opposing camps. I believe there is far more that unites us, as Americans and members of the Clemson family. These include: • Our core Clemson values of honesty, integrity and respect for others. • Our respect for the military and support for our servicemen and women. • Our respect for the Constitution they are sworn to uphold, which is clear in placing ultimate authority in our civilian Commander-in-Chief, the President. Passion about issues, commitment to candidates and participation in the democratic process are all vitally important. But when the voting is done, we have one President and he is President of us all. After November 6, our nation will need to work together to solve the many challenges that lie ahead. Engaging in positive dialogue and choosing the right time and place to voice our opinions will help us do that. Sincerely, — Jim Barker

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