Jacob D. Mater was born in Parke County, Indiana, on May 11, 1846, to Ira Mater, a famous circuit-riding preacher in the Wabash Valley region of Indiana. Growing up, Jacob attended public schools in Parke County while working on his parents’ farm.

On January 25, 1865, he enlisted for one year as a private in Company I of the 149th Indiana Infantry. Many young Parke County men joined him in the regiment, including Mater’s friends Marion Goss and Joseph Noble. Mater’s brother Hiram served as captain of Company I, and Jacob received a promotion to corporal on January 30. The regiment served on garrison duty in Tennessee and Alabama, where they accepted the surrender of Confederate Generals Philip Roddey and Leonidas L. Polk. Mater mustered out of service on September 27, 1865, in Nashville, Tennessee.

After the war, Mater returned to his father’s farm in Parke County, where he briefly worked as a school teacher. On August 25, 1870, he married Mary Ann Galey, the daughter of a Parke County farmer. She later gave birth to a son who died in infancy. The newlywed Mater attended Westfield College in Illinois for two months, but in 1871 he began studying medicine under his friend Marion Goss. Mater enrolled in the University of Virginia School of Medicine in the fall of 1872, graduating on July 3, 1873. After graduation, Mater practiced medicine in Rosedale, Indiana, for six months before settling in Bridgeton, a small community in Parke County.

Mater actively participated in the Marion Galley post of the Grand Army of the Republic, eventually serving as the post’s quartermaster. He also joined the Parke County Medical Society and the Indiana Medical Society. In 1879, however, he was expelled from the latter organization for allegedly advertising “secret nostrums” under his name. The expulsion appears to have been a misunderstanding, as the society subsequently reinstated his membership.

Mary Mater died on October 6, 1875, leaving no surviving children. On November 19, 1876, Jacob married Isabel Webster. She gave birth to a son named Bruce soon after, but he died at ten months old. Mater travelled around the region offering lectures, and Isabel accompanied her husband on his travels.

Although Mater maintained a thriving practice, he suffered from health ailments, particularly breathing problems, stemming from his time in military service. He applied for a pension and began receiving payments on May 15, 1890. He died from myocarditis on April 16, 1914, and was buried in Bridgeton Cemetery. His widow Isabel received a pension for her service until her death on September 2, 1927.