Question: The 15:17 to Paris was based on an autobiography about a man who stopped a gunman on a Paris-bound train on what date?

Context paragraphs:
Alek Skarlatos: Aleksander Reed "Alek" Skarlatos ( born October 10, 1992) is an American Oregon Army National Guardsman specialist who, along with fellow Americans Spencer Stone and Anthony Sadler, a Briton and two Frenchmen, stopped a gunman on a Paris-bound train travelling from Amsterdam via Brussels in August 2015.  He has been awarded the United States Army Soldier's Medal from U.S. President Barack Obama, and has received France's highest decoration, the Legion of Honour, from French president François Hollande as well as the medal of Arras, France.  Skarlatos competed on season 21 of ABC's "Dancing with the Stars" with pro dancer Lindsay Arnold, and finished in third place.

List of Densha Otoko chapters: There are four manga adaptations of the "Densha Otoko" novel.  All four adaptations are based on the purportedly true story of a 23-year-old otaku who intervened when a drunk man was harassing several women on a train.  The otaku ultimately begins dating one of the women.  The four adaptations in order of publication are: "Train_Man: Densha Otoko" by Hidenori Hara; "Densha Otoko: The Story of a Train Man Who Fell in Love With A Girl" by Wataru Watanabe; "Train_Man: Go, Poison Man!"  written by Hitori Nakano and illustrated by Daisuke Dōke and "Train_Man: A Shōjo Manga" by Machiko Ocha.

Lagny-Pomponne rail accident: The Lagny-Pomponne rail disaster occurred on 23 December 1933, between Pomponne and Lagny-sur-Marne (), 20 km east of Paris, when the 4-8-2 locomotive of the express for Strasbourg crashed at 110 km/hr (65 mph) into the rear of an auxiliary train bound for Nancy, which was stopped on the railway.  The impact crushed and splintered the last five cars of the Nancy train, older wooden cars pressed into service for the holidays.  Both trains were full of people going home to their families for Christmas.  204 people died and 120 were injured.  It is second the worst railway disaster in French history, after the 1917 Saint-Michel-de-Maurienne derailment, and the worst ever in peacetime.

Stabbing of Spencer Stone: Spencer Stone, a-then United States Air Force senior airman, was stabbed on October 8, 2015, in downtown Sacramento, California.  Stone was stabbed by a 28-year-old California man, James Tran.  The event received considerable attention in the U.S., in part that Stone helped stop a gunman on a Paris-bound train traveling from Amsterdam via Brussels two months earlier in August 2015.

The 15:17 to Paris: The 15:17 to Paris is an upcoming American biographical drama film directed by Clint Eastwood and written by Dorothy Blyskal, based on the autobiography "The 15:17 to Paris: The True Story of a Terrorist, a Train, and Three American Heroes" by Jeffrey E. Stern, Spencer Stone, Anthony Sadler and Alek Skarlatos, about the 2015 Thalys train attack; it will star Stone, Sadler, and Skarlatos as themselves.

Grand Trunk Station (South Paris): The Grand Trunk Station was a historic railroad station in South Paris, Maine.  The station was built in 1883 by the Grand Trunk Railroad linking South Paris with Montreal and Portland, Maine.  Trains began regular operation between Portland and the depot on the Paris side of the town line with Oxford at Widow Merrill's crossing October 8, 1849, even though the station was listed as "North Oxford" in timetables.  The first train into South Paris village was a contractor's engine called the Jenny Lind on January 1, 1850.  It ran carefully across temporary bridgework up to where the station was being built, as a means of satisfying the investors worries from Paris Hill to counter their threat of withdrawing their support and money if there was not a train in the village proper on that date (an engine operating by itself without cars met the ruling of a train).  The Androscoggin bridge was completed March 15, 1850, with regular service to Portland from the present day station grounds to Portland beginning on the 18th.  On December 30, 1879, the Norway Branch Railroad opened, running from Norway village on a line 1.45 miles long to connect with the Grand Trunk Railroad at South Paris.

William James Stillman: William James Stillman (June 1, 1828 – July 6, 1901) was an American journalist, diplomat, author, historian, and photographer.  Educated as an artist, Stillman subsequently converted to the profession of journalism, working primarily as a war correspondent in Crete and the Balkans, where he served as his own photographer.  For a time, he also served as United States ambassador in Rome, and afterward in Crete during the Cretan insurrections.  He helped to train the young Arthur Evans as a war correspondent in the Balkans, and remained a lifelong friend and confidant of Evans.  Later in life, he seriously considered taking over the excavation at Knossos from Minos Kalokairinos, who had been stopped from further excavation by the Cretan Assembly; he was, however, prevented from pursuing that goal further by a failure to obtain a firman, or permission to excavate.  Stillman wrote several books, one of which, his "Autobiography of a Journalist", suggests that he viewed himself primarily as a writer.

Jason Sprinkle: Jason Sprinkle (November 6, 1969 - May 16, 2005) was a Seattle-based sculptor and guerrilla artist.  He was most famous for attaching a 700-pound ball and chain around the foot of Jonathan Borofsky's "Hammering Man" outside of the Seattle Art Museum and for various other illegal art sculptures left at Westlake Park.  These actions ended in July 1996 when Sprinkle's final sculpture caused a bomb scare and Sprinkle was briefly imprisoned.  After suffering a mental breakdown in jail, Sprinkle stopped making art and became a born again Christian.  He died in 2005 after being hit by a train.

Spencer Stone: Spencer Stone ( born 1992) is an American author, television personality and former United States Air Force staff sergeant.  Stone, along with fellow Americans Alek Skarlatos and Anthony Sadler, a Briton and two Frenchmen, stopped a gunman on a Paris-bound train travelling from Amsterdam via Brussels in August 2015.  Gaining international fame, Stone was recognized by U.S. Ambassador to France Jane D. Hartley for "his actions in saving countless lives" and by U.S. President Barack Obama, with a ceremony held at The Pentagon to honor Stone, Skarlatos and Sadler.  He was awarded the Airman's Medal and a Purple Heart.  French President Francois Hollande awarded Stone, as well his friends, the Legion of Honour, the highest French order for military and civil merits.  On October 8, 2015, Stone was stabbed by a California man, James Tran, 28, during a fight in downtown Sacramento.  He suffered life-threatening injuries and was rushed to UC Davis Medical Center.  Stone recovered, and was released from the hospital on October 15.  He was promoted to senior airman in late October and then staff sergeant in November 2015.

2015 Thalys train attack: On 21 August 2015, a shooting and stabbing incident took place on board a Thalys train in France on its way from Amsterdam to Paris.  The train had just crossed the border from Belgium into France and was traveling through Oignies in the department of Pas-de-Calais, when the perpetrator opened fire in a train carriage before being subdued by passengers, one of whom he stabbed.  Including the assailant, four people were injured, none fatally.  The incident is believed by French police to be an Islamist terrorist attack, although the gunman claimed the motivation was robbery due to hunger.  Several people who subdued the attacker were awarded France's highest decoration, the Legion of Honour, as well as other awards.

Supporting paragraphs: The 15:17 to Paris Alek Skarlatos
Answer: August 2015