His attempts to coerce Chief Charlo to sign the agreement nearly brought about a military clash. In the end, he convinced two subchiefs to sign and move to the reservation with a few of the Salish people. Garfield never convinced Charlo to sign, although the official treaty document voted on by Congress bore his forged mark.[138]
In 1876, Garfield developed a trapezoid proof of the Pythagorean theorem, which was published in the New England Journal of Education.[139] Mathematics historian William Dunham wrote that Garfield's trapezoid work was "really a very clever proof."[140] According to the Journal, Garfield arrived at the proof "in mathematical amusements and discussions with other members of congress."[141]
After his conversion experience in 1850, religious inquiry was a high priority for Garfield. He read widely and moved beyond the confines of his early experience as a member of the Disciples of Christ. His new, broader perspective was rooted in his devotion to freedom of inquiry and his study of history. The intensity of Garfield's religious thought was also influenced by his experience in combat and his interaction with voters.