Born in Philadelphia to John Bradford Wallace and Susan Binney, Wallace worked most of his life as a lawyer. He graduated from the University of Pennsylvania in 1833, was admitted to the bar in 1837, served as treasurer and librarian of the Law Association of Philadelphia, and wrote The Reporters in 1844.
According to Hampton L. Carson’s History of the Historical Society of Pennsylvania (1940), the appointment of John William Wallace to president of the society marked the end of its tradition of “venerable and venerated presidents.” Wallace began his tenure in April 1868 and served until 1883. During his time, Wallace oversaw several notable acquisitions, such as the Penn family papers and the bequest of several thousand pamphlets by Dr. George W. Fahnestock. Wallace also oversaw the Society's busy schedule of activities during the 1876 Centennial Exhibition, and he helped established the Pennsylvania Magazine of History and Biography, which was first issued in 1877. The purchase of the Patterson mansion was one of his final acts as president.
In November 1882, Francis Stokes, a lumber merchant and HSP member, offered to sell the society the Patterson mansion located on the southwest corner of 13th and Locust Streets. The three-story stone structure in modified Greek style had been constructed by John Hare Powel in 1832. It was the former home of General Robert Patterson, who had served in the War of 1812, the Mexican War, and the Civil War. HSP was enthusiastic about this new site, and within seven weeks raised the necessary funds to procure it. On February 1, 1883, with Wallace at the helm, the society purchased half of the original property, including the mansion. Though the mansion was architecturally sound, improvements had to be made to accommodate the Society's collections. Architect Addison Hutton drew up plans for the construction of a new building on the west side of the mansion—a spacious hall for Society meetings. Hutton also designed a fireproof storage area on the northeastern corner of the property.
Wallace, unfortunately, did not live to see the mansion's transformation. He died about a year after the purchase was made in 1884.
HSP has some of John William Wallace’s works, such as The Reporters, An old Philadelphian, Colonel William Bradford, the patriot printer of 1776: sketches of his life, and “Records of Philadelphia, 1702-1770” in our library. Manuscripts from Wallace’s ancestors can be found in the Bradford Family papers (#1676) and the Horace Binney papers (#1505).