Here is a brief excerpt from Wikipedia’s history of American football (during the period this story takes place):

From its earliest days as a mob game, football was a violent sport. The 1894 Harvard-Yale game, known as the “Hampden Park Blood Bath”, resulted in crippling injuries for four players; the contest was suspended until 1897. The annual Army-Navy game was suspended from 1894 to 1898 for similar reasons. One of the major problems was the popularity of mass-formations like the flying wedge, in which a large number of offensive players charged as a unit against a similarly arranged defense. The resultant collisions often led to serious injuries and sometimes even death.