The day Marvel fans have been waiting for has finally arrived! Captain America: Civil War opens in theaters nationwide, kicking off Marvel's Phase 3 in a huge way, with the entire Marvel Cinematic Universe divided against each other in an epic battle. Before these heroes square off on the big screen, some of the cast members came together in a new TV spot to sing a familiar song, the Battle Hymn of the Republic, in a new TV spot.

The Mashable Twitter page debuted this viral video, which starts off with Chris Evans talking about how Steve Rogers left Brooklyn to join the war, and ultimately became a "superhero." He's eventually joined by a number of his Captain America: Civil War cast mates, such as Robert Downey Jr., Anthony Mackie, Elizabeth Olsen, Sebastian Stan and Chadwick Boseman, who start humming, then singing, the Battle Hymn Republic as Chris Evans continues to discuss Steve Rogers' heroic exploits. We don't get to see any actual footage from Captain America: Civil War, but this video will certainly get you in the right frame of mind before seeing the movie this weekend.

Steve Rogers leads a newly formed Avengers team in their continued efforts to safeguard humanity. The action is set in the aftermath of Avengers: Age of Ultron. Following another incident involving the Avengers that results in collateral damage, political pressure mounts to install a system of accountability, headed by a governing body to oversee and direct the team. The new status quo fractures the Avengers, resulting in two camps, one led by Steve Rogers and his desire for the Avengers to remain free to defend humanity without government interference, and the other following Tony Stark's surprising decision to support government oversight and accountability.

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Team Iron Man includes Tony Stark (Robert Downey Jr.), Black Widow (Scarlett Johansson), Vision (Paul Bettany), War Machine (Don Cheadle) and the new characters T'challa (Chadwick Boseman) and Spider-Man (Tom Holland). Team Cap includes Captain America (Chris Evans), The Falcon (Anthony Mackie), Scarlet Witch (Elizabeth Olsen), Hawkeye (Jeremy Renner), Ant-Man (Paul Rudd) and The Winter Soldier (Sebastian Stan). Captain America: Civil War also stars Frank Grillo as Crossbones and William Hurt, reprising his role from The Incredible Hulk as Thaddeus Ross.

Marvel's Civil War has been projected to take in between $175 million and $200 million in its opening weekend, but it could come in even higher than that. The movie currently has an impressive 92% Fresh rating on Rotten Tomatoes, so we'll have to wait and see if it can surpass the $200 million mark this weekend. Be sure to check back on Sunday to see how Captain America: Civil War fared in theaters in this first weekend of the summer movie season, but until then, take a look at this unique TV spot below.