He was born in New York City, the oldest of ten children of Edward H. Fletcher, a publisher, and Mary Augusta (Hill) Fletcher. Both his parents were natives of Cavendish, Vermont, and he was a descendant of Robert Fletcher, who settled in Concord, Massachussets, in 1630.
After early education in the New York public schools, Fletcher spent three years at the New York Free Academy (later the College of the City of New York), where he pursued a classical program of studies.
In 1864 he won a competitive examination for appointment to the United States Military Academy at West Point.
Himself a graduate of Dartmouth, he turned to that college, and in 1871 the Thayer School of Engineering was founded at Dartmouth according to his plan.
Graduating in 1868, he was commissioned a second lieutenant and served a year on garrison duty in Texas. He was then called back to West Point as instructor in mathematics under Prof. Albert E. Church.
At this time General Sylvanus Thayer, widely known as the "father" of the Military Academy, was planning to establish and endow his own engineering school which would emphasize a broader liberal arts education for young engineers.
Himself a graduate of Dartmouth, he turned to that college, and in 1871 the Thayer School of Engineering was founded at Dartmouth according to his plan.
Through the recommendation of Professor Church and with the approval of President Asa Dodge Smith of Dartmouth, the leadership in this unique educational venture was entrusted to Fletcher, then a young instructor of twenty-three.
He resigned his army commission at the end of 1870 to accept the new post.
To his background of classical education his experience at West Point had added a knowledge of engineering teaching, for West Point from the time of its founding in 1802 until shortly before the Civil War had been primarily an engineering school, and a number of pioneer American engineering texts originated there.
During the first few years Fletcher was the only instructor at the new Thayer School, his teaching spanning the entire range from drafting to hydrodynamics, from surveying to practical astronomy, from materials to machine design, and from bridges to engines.
Happily, engineering techniques at this time were far simpler than they became later, and less expertness and special experience were essential in teaching.
Fletcher died of pneumonia at Hanover and was buried in the Old Cemetery there, a short distance from the home he had occupied for over sixty years.
Guide, philosopher, and friend to generations of Thayer School alumni, he retired in 1918, at which time Dartmouth honored him with the Doctor of Science degree. The college had already awarded him the honorary degrees of A. M. in 1871 and Ph. D. in 1881. Fletcher gave his full and active support to the American Society for Engineering Education, of which he was president in 1901-02, and to the American Society of Civil Engineers. He was a prodigious worker. For many years he served as president of the New Hampshire State Board of Health. His hobbies included archeology and the study of volcanoes. While in his eighties he wrote, with Jonathan Parker Snow, "A History of the Development of Wooden Bridges" (Transactions of the American Society of Civil Engineers, vol. XCIX, 1934), a major contribution on the subject.
Fletcher gave his full and active support to the American Society for Engineering Education, of which he was president in 1901-02, and to the American Society of Civil Engineers.
A gentleman of the old school, Fletcher was sincerely religious and rigidly temperate, avoiding alike, it was said, tobacco, alcohol, and profanity.
He was a member of the American Society of Civil Engineers.
A born teacher and a man of exemplary personality and character, Fletcher quickly won the respect and admiration of all his students and colleagues.
On July 2, 1872, he married Ellen M. Huntington of Hanover, New Hampshire. They had two children, Robert Huntington and Mary Adeline.
