In 1839 he accompanied Albert Sidney Johnston, David Burnet, I. W. Burton, and Thomas J. Rusk as a commission to propose to the Cherokee Indians that they leave Texas upon payment for their improvements by the republic. The Cherokee refused the offer on July 16, 1839, which resulted in hostilities with the military. Mayfield participated in the ensuing battles as aide-de-camp for Brigadier General K. H. Douglas and authored field reports for Johnston. Mayfield represented Nacogdoches County in the Fifth and Sixth congresses (1840-42) and introduced the Franco-Texian Bill. From February 8, 1841, to September 7, 1841, Mayfield served as secretary of state under Mirabeau B. Lamar, except for the period from April 30 to September 7, when Joseph Waples and Samuel A. Roberts served consecutively in his place. On October 28, 1841, Mayfield relocated his family to La Grange in Fayette County, where he continued to practice law.
During a speech in the Texas House of Representatives on January 4, 1842, Mayfield disparaged fellow congressman David S. Kaufman. The two men exchanged gunfire and Kaufman ultimately died from a wound to the abdomen, but the encounter was considered a fair fight and Mayfield did not face charges. On September 16, 1842, Mayfield assembled a company of fifty-three volunteers from La Grange, to follow Capt. Nicholas Dawson in an attempt to repel Gen. Adrián Woll's Mexican army from San Antonio. His group, joined by others under the command of Jesse Billingsley and W. J. Wallace, arrived at the scene of the Dawson massacre on Salado Creek while it was occurring. Mayfield, as the commanding officer, determined that his group was too far outnumbered and remained in the distance until the following day, when he joined the command of Mathew Caldwell. Mayfield commanded one of the battalions but opposed pursuing Woll further south due to overwhelming force and the inevitable arrival of Mexican reinforcements.
In 1842 Mayfield was a member of the Somervell expedition but did not join the subsequent Mier expedition. Congressman Robert Potter died in 1842 and bequeathed one-third of his estate to Sophia as well as his favorite horse “Shakespeare” to James. In 1843 he presented himself as a candidate for major general of the Texas army but removed himself from consideration because, he said, of ill health. It is probable, however, that accusations of cowardice during the Woll invasion leveled by Mathew Caldwell and Edward Burleson had much to do with his decision. Mayfield represented Fayette County at the Convention of 1845 and in September challenged Burleson to a duel but did not go through with the engagement.
In 1846 Mayfield served as an inspector of the La Grange Female Institute and in April he helped organize the Democratic party in Texas. On July 28, 1849, he killed Absolom Bostwick in self-defense during a political argument regarding the special election of the sheriff. Bostwick’s death led to the discovery of an organized gang of thieves operating from Missouri to the Rio Grande. In July 1850 Mayfield was one of a committee appointed in a meeting at La Grange to consider insurrectionary movements in Santa Fe County. Sophia died in La Grange on March 2, 1852 and James passed away later that year on December 3. The Mayfields were buried in the front yard of their home in La Grange, but relocated to the La Grange Cemetery in 1858. On March 6, 2004, the Daughters of the Republic of Texas held a dedication ceremony to adorn the grave with a bronze medallion identifying Mayfield as a “Defender of the Republic of Texas.” Source
Old La Grange City Cemetery