Despite his small size, Warren became a starter as a freshman for Princeton's football team—considered the best in the United States at the time.

The following newspaper account describes Warren's quick progression to varsity:"In his freshman year he began work by trying for his class team.

His work soon caused "Snake" Ames, then captain of the Princeton eleven, to invite the smooth-faced youth to take a place at right end on the scrub team.

"[4]Warren became a star in his sophomore season of 1890 and was rewarded with his selection as one of two ends to be named to the 1890 College Football All-America Team.

[5] Fellow end Jesse Riggs was selected as captain of the 1891 Princeton football team, but he resigned the position before the season began.

[7] Accordingly, The World of New York wrote in 1891: "The captaincy of a football team was never so important as now, and McClung of Yale, Warren of Princeton, and Trafford of Harvard are names which will be 'oft upon the lips of man' in the next two months.

Warren has spent much of his time this season on the field in directing the play without taking a hand in the game.

"[2] The profile described Warren as one of the "heroes of football" and focused on his leadership role as captain of the Princeton team:"There are critics of the game who say that Capt.

In late December 1891, Warren walked out of a friend's house in Washington, D.C at 6 o'clock on a cold morning without an overcoat.

Warren's uncle told reporters that his nephew's story of what had happened over the past days was largely incoherent and that the family attributed his actions to his football injuries.