The film is based on Doug Stanton's non-fiction book Horse Soldiers, which tells the story of U.S. Army Special Forces sent to Afghanistan immediately after the September 11 attacks and up to the fall of Mazar-i-Sharif.

[5] Mitch Nelson, a U.S. Army captain with Green Berets Operational Detachment Alpha (ODA) 595, is moving into a new home with his wife and daughter on September 11, 2001, after receiving an assignment to staff duty under Lieutenant Colonel Bowers.

After being briefed and evaluated by COL Mulholland, Commander of 5th Special Forces Group, Nelson and 595 are picked to fight alongside Northern Alliance leader Abdul Rashid Dostum.

[6] They land 40 miles south of Mazar-i-Sharif, the country's fourth-largest city and a longtime stronghold of the Taliban, where they meet Dostum.

Six of the 12 members, led by Nelson, leave with Dostum to the mountains, while the other six remain in a fortified camp nicknamed "the Alamo" under Spencer's command.

The two eventually reconcile and after splitting off a three-man element under SFC Sam Diller to strike a Taliban supply route and being joined by Spencer's half of ODA 595, continue to work together.

Spencer is critically injured by a suicide bomber, and the team is about to be overrun under heavy Taliban and Al-Qaeda pressure when Dostum returns with his forces.

Carrying out the U.S. Army's first cavalry charge of the 21st century, the American and Northern Alliance forces disperse the Taliban and al-Qaeda, and Dostum tracks down and kills Razzan.

[13] On November 14, 2016, Austin Stowell was cast in the film to play Staff Sergeant Fred Falls, an American soldier on the elite U.S. Special Forces team.

[25] The films postscript reads as follows: "Against overwhelming odds, all twelve members of the U.S. Army Special Forces ODA 595 survived their mission.

[27] In the United States and Canada, 12 Strong was released on January 19, 2018, alongside Den of Thieves and Forever My Girl, as well as the wide expansions of Phantom Thread, I, Tonya and Call Me by Your Name, and was projected to gross $15–20 million from 3,002 theaters in its opening weekend.

The website's critical consensus reads, "12 Strong has a solid cast, honorable intentions, and a thrilling, fact-based story — all of which are occasionally enough to balance a disappointing lack of depth or nuance.

Gleiberman notes that the soldiers riding on horseback do not amount to much, but praises the director and cinematographer for using the New Mexico locations to conjure the landscape of Afghanistan, calling it the most impressive aspect of the film.