Editing James A. Garfield (section)

===Legal career and other activities===
In 1865, Garfield became a partner in the law firm of a fellow Disciple of Christ, [[Jeremiah Black]]. They had much in common, except politics: Black was an avid Democrat, having served in the cabinet of President [[James Buchanan]].{{sfn|Peskin|1978|p=270}} The next year, Black was retained by some pro-Confederate northern civilians who had been found guilty of treason in a military court and sentenced to death. Black saw an opportunity to strike a blow against military courts and the Republicans.{{sfn|Peskin|1978|p=271}} He had heard Garfield's military speeches, and learned of not only his oratory skills but also his resistance to expansive powers of military commissions. Black assigned the case to Garfield one week before arguments were to be made before the U. S. Supreme Court. When Black warned him of the political peril, Garfield responded, "It don't make any difference. I believe in English liberty and English law."{{sfn|Peskin|1978|p=272}} In this landmark case, ''[[Ex parte Milligan]],'' Garfield successfully argued that civilians could not be tried before military tribunals, despite a declaration of martial law, as long as civil courts were still operating. In his first court appearance, Garfield's oral argument lasted over two hours, and though his wealthy clients refused to pay him, he had established himself as a preeminent lawyer.{{sfn|Peskin|1978|p=271}}

During Grant's first term, Garfield was discontented with public service and in 1872 again pursued opportunities in the law. But he declined a partnership offer from a Cleveland law firm when told his prospective partner was of "intemperate and licentious" reputation.{{sfn|Peskin|1978|p=347}} In 1873, after Chase's death, Garfield appealed to Grant to appoint Justice [[Noah H. Swayne]] Chief Justice, but Grant appointed [[Morrison R. Waite]].{{sfn|McFeely|1981|pp=387–389, 392}}
[[File:Garfield Pythagoras.svg|thumb|upright=.75|right|Garfield's proof of the Pythagorean theorem features a right triangle within a trapezoid.]]
In 1871, Garfield traveled to [[Montana Territory]] to negotiate the removal of the [[Bitterroot Salish]] tribe to the [[Flathead Indian Reservation]].<ref>{{cite journal |last1=Holmes |first1=Oliver W. |title=Peregrinations of a Politician: James A. Garfield's Diary of a Trip to Montana in 1872 |journal=Montana The Magazine of Western History |date=Autumn 1956 |volume=6 |issue=4 |pages=34–45 |jstor=4516109 |url=https://www.jstor.org/stable/4516109 |access-date=February 25, 2021 |archive-date=March 18, 2021 |archive-url=https://web.archive.org/web/20210318144706/https://www.jstor.org/stable/4516109 |url-status=live }}</ref> Having been told that the people would happily move, Garfield expected an easy task. Instead, he found the Salish determined to stay in their [[Bitterroot Valley]] homeland. 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.<ref>{{cite journal |last1=Bigart |first1=Robert |title='Charlot loves his people': The Defeat of Bitterroot Salish Aspirations for an Independent Bitterroot Valley Community |journal=Montana The Magazine of Western History |date=Spring 2010 |volume=60 |issue=1 |page=27 |jstor=25701716 |url=https://www.jstor.org/stable/25701716 |access-date=February 25, 2021 |archive-date=March 18, 2021 |archive-url=https://web.archive.org/web/20210318144711/https://www.jstor.org/stable/25701716 |url-status=live }}</ref>

In 1876, Garfield developed a [[Garfield's proof of the Pythagorean theorem|trapezoid proof]] of the [[Pythagorean theorem]], which was published in the ''[[New England Journal of Education]]''.<ref>{{Cite journal |last=G. |first=J. A. |date=1876 |title=PONS ASINORUM |url=https://www.jstor.org/stable/44764657 |journal=New England Journal of Education |volume=3 |issue=14 |pages=161 |jstor=44764657 |issn=2578-4145}}</ref> Mathematics historian [[William Dunham (mathematician)|William Dunham]] wrote that Garfield's trapezoid work was "really a very clever proof."<ref>{{cite book |last1=Dunham |first1=William |author-link1=William Dunham (mathematician)|title=The Mathematical Universe: An Alphabetical Journey Through the Great Proofs, Problems, and Personalities |url=https://archive.org/details/mathematicaluniv0000dunh |url-access=registration |publisher=Wiley & Sons |page=[https://archive.org/details/mathematicaluniv0000dunh/page/99 99] |year=1994 |bibcode=1994muaa.book.....D |isbn=9780471536567 }}</ref> According to the ''Journal'', Garfield arrived at the proof "in mathematical amusements and discussions with other members of congress."<ref>{{cite web|url=https://www.maa.org/press/periodicals/convergence/mathematical-treasure-james-a-garfields-proof-of-the-pythagorean-theorem|title=Mathematical Treasure: Garfield's Proof of the Pythagorean Theorem|publisher=Mathematical Assoc. of America|last=Kolpas|first=Sid J.|access-date=December 22, 2021|archive-date=December 6, 2021|archive-url=https://web.archive.org/web/20211206052548/https://www.maa.org/press/periodicals/convergence/mathematical-treasure-james-a-garfields-proof-of-the-pythagorean-theorem|url-status=live}}</ref>

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.<ref>William C. Ringerberg, "The Religious Thought and Practice of James A. Garfield" ''Old Northwest'' (1982) 8#4 pp 365–382.</ref><ref>Allan Peskin, "James A. Garfield, Historian" ''The Historian'' 43#4 (1981), pp. 483–492 [https://www.jstor.org/stable/24446440 online] {{Webarchive|url=https://web.archive.org/web/20210308155753/https://www.jstor.org/stable/24446440 |date=March 8, 2021 }}.</ref>