Answer:
The Rough Riders was the name given to the 1st United States Volunteer Cavalry, one of the three cavalry regiments raised in 1898 for the Spanish-American War and the only one of the three who engaged in battle.
The US military was weak, left with few men after the end of the Civil War about 30 years ago. As a result, President William McKinley called on 1250 volunteers to contribute to the war effort. When Colonel Wood became commander of the 1st Cavalry Brigade (consisting of 1st Cavalry, 106th Cavalry, and 1st Volunteer Cavalry), the Rough Riders then became the Roosevelt's Rough Riders, named after their new commander, Theodore Roosevelt, the future president of the United States.
In 1899, a year after the war, Theodore Roosevelt wrote a book telling the adventure of this regiment, which became a success and made him well known among the American society.
