"Freedom Song" draws inspiration from both Boston and Washington. Diamond wrote it following April's Boston Marathon bombings and a visit to Walter Reed National Military Medical Center in the Washington suburb of Bethesda, Md.
"I, like so many other Americans, felt helpless during the recent attacks in Boston and wanted so much to reach out and not only help those people affected in a direct way but to lift their spirits as well, and let them know they were not alone; that the entire American community felt a close kinship with them," Diamond said in a statement. "I was inspired to devote myself to the creation of a new song which expressed my love for this country and its two greatest assets: the spirit of its people and the freedoms it has afforded us all by law."
Diamond's performance came during the Nationals' In-Game Military Salute, a tradition the team has during each home game. On his final note, the huge holiday crowd -- including those lined up behind him in the Presidents Club -- let out a big ovation.
"Freedom Song" starts off with the lyrics, "Two hundred years and more; And here we are today; With freedom still our guiding light; Defending it with all our might."
The chorus talks about how America won't be taken down "though some may try," because the country will "stand our ground," and hold onto freedom that "can't be denied." The song ends with the verses, "We know that they can never take us down; And freedom's why; Together we can raise up freedom's flag; Where eagles fly."
Diamond and his music played a big role in the healing process that took place at stadiums across Major League baseball following the bombings. The Rock and Roll Hall of Famer led Fenway Park in an emotional singing of "Sweet Caroline" during a game soon after the tragedy. Other Major League teams, including the Nationals, also played it to honor Boston.
"Freedom Song," expresses the qualities Diamond has seen in his many years of travels across the U.S.
"I've seen this spirit all over the country," Diamond told USA Today. "So many people have opened their doors to help me get the message across, which is America is worth loving and we should be proud of what we have and be very careful to protect it."
Andrew Simon is a reporter for MLB.com. Follow him on Twitter @HitTheCutoff. This story was not subject to the approval of Major League Baseball or its clubs.