Sadler, along with his friends Alek Skarlatos and Spencer Stone and several other passengers stopped a gunman on a Paris-bound train travelling from Amsterdam via Brussels in August 2015, gaining international recognition for their role in the event.
He, Skarlatos and Stone co-authored a memoir, titled The 15:17 to Paris, published in August 2016, which detailed the events leading up to the attack, which occurred a year prior to the release of the book.
Clint Eastwood directed a biographical film with the same title based on Sadler, Skarlatos and Stone's memoir, starring them, along with actresses Jenna Fischer and Judy Greer.
On August 21, 2015, Sadler and his childhood friends Alek Skarlatos and Spencer Stone, were traveling together during a sightseeing vacation in Europe when they boarded Thalys train 9364 from Amsterdam bound to Paris via Brussels.
[11] The White House expressed gratitude for "courage and quick thinking of several passengers, including U.S. service members, who selflessly subdued the attacker..."[12] U.S. President Barack Obama telephoned the three Americans, thanking them for their heroic actions.
[13] General Philip M. Breedlove of the U.S. European Command in Stuttgart, added his voice, calling the three Americans heroes for their actions which "clearly illustrate the courage and commitment our young men and women have all the time, whether they are on duty or on leave.
[17] According to a decree published on September 20, 2018, Sadler (along with Stone and Skarlatos) were naturalized as citizens of France,[18] and according to Le Monde retroactively to April 2018, when they applied for nationality.
[20] Months later in 2016, Sadler, Alek Skarlatos and Spencer Stone started working on a memoir, titled The 15:17 to Paris, detailing the events of the train attack.
[23] In July 2017, it was announced that Clint Eastwood would direct the upcoming biographical film titled after Stone, Skarlatos and Sadler's memoir, starring the three authors as themselves, along with actresses Jenna Fischer and Judy Greer.