This Sunday's slate of football games will once again spur a national debate about which players are sitting, kneeling, standing, raising fists, linking arms, etc., during the pregame performance of the "Star-Spangled Banner" in solidarity or opposition with San Francisco 49ers quarterback Colin Kaepernick. During the preseason, he made a point of not standing for the national anthem as a protest of racial injustice and the shootings of unarmed black people in America, saying, "I am not going to stand up to show pride in a flag for a country that oppresses black people and people of color. To me, this is bigger than football and it would be selfish on my part to look the other way. There are bodies in the street and people getting paid leave and getting away with murder."

He's been called everything from a hero to a traitor, along with some very ugly racial slurs, and while so many people have an opinion on what this backup quarterback does, we wonder how many people know the history of our national anthem and why it's become a pre-game staple at every sporting event.

The song's origins come from the War of 1812, specifically the Battle of Baltimore in 1814. Lawyer Francis Scott Key, aboard a British ship in an effort to negotiate the release of an imprisoned American doctor, watched as the city was bombarded with rockets. At the dawn of Sept. 14, 1814, he saw that the country's flag was still flying above Fort McHenry, inspiring him to write the poem "Defence of Fort M'Henry." It was published in a newspaper and, with Key's assistance, adapted into a song by publisher Thomas Carr. He put the words to the tune of "To Anacreon in Heaven," which originated in an 18th-century London social club as a tribute to a Greek poet known for his drinking songs. Key had previously used the melody for his tribute to soldiers of the Barbary Wars, which were fought between the United States and several countries in the Ottoman Empire's hold on northern Africa. It was called "When the Warrior Returns." He wrote it in 1805 and it included the lyrics, " And pale beamed the Crescent, its splendor obscured/By the light of the star-spangled flag of our nation."

To Anacreon in Heaven:

When the Warrior Returns:

The version currently performed at sporting events only uses the first verse of Key's original poem. The three remaining verses are a little more focused on the violence of the battle, and one couplet has been highlighted by many defending Kaepernick's protest: "No refuge could save the hireling and slave/ From the terror of flight, or the gloom of the grave." As the Intercept reports, many American slaves fled from their owners and joined the British in the war, and Key, himself a slave owner, seemingly reveled in the deaths of those on the English side. Years later, Key was a district attorney for Washington, D.C. and indicted an abolitionist newspaper for their report on how local police were attacking black residents. "Key was furious and indicted the newspaper for intending 'to injure, oppress, aggrieve & vilify the good name, fame, credit & reputation of the Magistrates & constables of Washington County.'" So, basically, his anger resembles that of the people who call Kaepernick unpatriotic and ungrateful to law enforcement and the military.

"The Star-Spangled Banner" gained popularity throughout the 19th century, competing with "Hail, Columbia," a song written by Philip Phile in 1789 George Washington's inauguration, as a national anthem. Dr. Oliver Wendell Holmes, Sr., the father of the famed Supreme Court judge, even wrote an additional verse in 1861, inspired by the Civil War: "When our land is illumined with Liberty's smile, If a foe from within strike a blow at her glory/Down, down with the traitor that dares to defile/The flag of her stars and the page of her story!/By the millions unchained who our birthright have gained/ We will keep her bright blazon forever unstained!"

Hail, Columbia

Decades later, the song would formally become a part of military occasions, and an informal staple of July 4th celebrations. President Woodrow Wilson ordered it to be played at military functions in a 1916 directive, and then had five popular musicians of the era, including John Philip Sousa, create a standardized version of the "Banner." A brass band's rendition of the anthem during a 1918 World Series matchup between the Red Sox and Cubs helped establish it as a gameday ritual of players and fans standing in respect.

Earlier that year, Maryland Congressman John Charles Linthicum, who served the area that included Fort McHenry, submitted the first of his six bills to establish "The Star-Spangled Banner" as the United States' anthem. The Veterans of Foreign Wars organization got millions of people to sign a petition urging the government to adopt the "Banner" as our signature song, and even had two women, Elsie Jorss-Reilley and Grace Evelyn Boudlin, sing the song for the House Judiciary Committee to prove that it wasn't too difficult to perform. On March 3, 1931, president Herbert Hoover signed a law designating it as the United States' official anthem.

The concern over singing adequately singing the anthem range aren't unfounded. According to an article from the National Museum of American History, which is part of the Smithsonian Institution in Washington, D.C., the octave-plus range of the notes in the song is often a hurdle, or an outright dealbreaker, for people asked to perform it. As they share, folk musician Pete Seeger once assured an audience that he'd perform it in a low-enough key that they could sing along.

According to Sports Illustrated, the "Banner" became tradition at baseball games in the World War II era. One of the first notable controversies over its performance came in 1968, when singer and guitarist Jose Feliciano took liberties with the song before a World Series game in Detroit. Heard now, it's relatively tame but at the time, with Vietnam protests growing, his take on it was very controversial. The next year, Jimi Hendrix famously did a version of the anthem at Woodstock, using distorted improvisations and feedback squalls to simulate military bombings. Those two performances paved the way for later interpretations, like Marvin Gaye's soulful, synth-backed interpretation at the 1983 NBA All-Star Game, and Whitney Houston's epic rendition at the Super Bowl in 1991.

Like most times "The Star-Spangled Banner" is sung on nationally televised events now, Houston's version relied on pre-recorded vocals. It's a solid strategy to help combat the possibility of technical difficulties and the nerves that accompany performing the song in front of thousands of people in person and millions watching at home. Imagine forgetting the words or having a missed note exacerbate your anxiety. Deadspin's Drew Magary detailed this in an article about his rendition in front of a crowd and a veteran color guard at a minor league baseball game, after awkwardly rehearsing in front of his laughing children: "The second I began singing, I split in two. There was one Drew, who was doing the singing. And there was a second Drew, who was evaluating the first Drew's singing the entire time. I felt my control of the second Drew was much stronger than my control of the first."

10 Worst National Anthem Performances Ever

Sometimes the singers can't hear themselves, sometimes they try and fail to hit certain notes in the pursuit of vocal gymnastics, sometimes they forget the words, and sometimes, like in the case of Lucy Lawless, they have a wardrobe malfunction. And certain people take this seriously. As controversial as the Feliciano, Hendrix, Gaye and Houston performances were, there have been plenty of worse examples since, such as Roseanne Barr's intentionally irreverent 1990 version. While federal law actually mandates the way veterans in and out of uniform have to position themselves, whether it's saluting or holding their hands, in 2011, Indiana State Senator Vaneta Becker actually proposed a law that would fine performers if they didn't perform the song correctly. As a local ABC affiliate reported, "Becker's bill would require all schools, including kindergarten through college, to enter into performance contracts with people who perform the anthem at school events. Those who don't perform it according to standards that would be set by the state Department of Education could be fined $25."

So, the next time you see a sporting event where athletes behave in a certain way during the performance of "The Star-Spangled Banner," or some musicians decide to put their own interpretation on it, for better or worse, at least remember that it's a song with a complicated history, from its British melody and slave-owning writer to how modern Americans choose how to sing, remember and respect it.