A Study in Scarlet - Facts

 

Watson first introduces himself as part of the Northumberland Fusiliers. The Royal Northumberland Fusiliers was an infantry regiment of the British Army. 

He was involved in the Second Afghan War, and it is where he was wounded. The Second Anglo-Afghan War was a military conflict fought between the British Raj and the Emirate of Afghanistan from 1878 to 1880. The war was part of the Great Game between the British and Russian empires.

Sherlock Holmes and Dr Watson share lodgings in 221B Baker Street in London. 221B Baker Street is the fictional London address of the detective Sherlock Holmes and is the real-world location of the Sherlock Holmes Museum.

When Sherlock Holmes introduces himself, he says he is good at singlestick. Singlestick is a martial art that uses a wooden stick as its weapon. It began as a way of training soldiers in the use of backswords.

Dr Watson compares Sherlock Holmes to Dupin, a character by Edgar Allan Poe. Le Chevalier C. Auguste Dupin is a fictional character created by Edgar Allan Poe. Dupin made his first appearance in Poe's 1841 short story "The Murders in the Rue Morgue", widely considered the first detective fiction story. 

Another detective he mentions is Lecoq by Gaboriah. Monsieur Lecoq is a novel by the nineteenth-century French detective fiction writer Émile Gaboriau. The novel depicts the first case of Monsieur Lecoq, an energetic young policeman who appears in other novels by Gaboriau.

The part in America takes place in Utah. Utah is a landlocked state in the Mountain West subregion of the Western United States. It is one of the Four Corners states, sharing a border with Arizona, Colorado, and New Mexico.

When the Mormons find John and Lucy in a desperate situation, John knows that Joseph Smith was the founder of the faith. Joseph Smith Jr. was an American religious leader and the founder of Mormonism and the Latter Day Saint movement. Publishing the Book of Mormon at the age of 24, Smith attracted tens of thousands of followers by the time of his death fourteen years later. 

One of the Mormons is Bringham Young, a real person. Brigham Young (June 1, 1801 – August 29, 1877) was an American religious leader and politician. He was the second president of the Church of Jesus Christ of Latter-day Saints (LDS Church) from 1847 until his death in 1877. 

The way Arthur Conan Doyle portrait the Mormons was based on the Danites. The Danites were a fraternal organization founded by Latter Day Saint members in June 1838, in the town of Far West, Caldwell County, Missouri. During their period of organization in Missouri, the Danites operated as a vigilante group and took a central role in the events of the 1838 Mormon War.