On June 24, 1896, Thacher wed Eliza Seely Blake in
New Haven. Although Blake herself was a graduate of the
University of California (1895), her family were Yale alumni as well. Her father, Charles Thompson Blake, had graduated with a BA in 1847, and her grandfather
Eli Whitney Blake had graduated with a BA in 1816. The couple shared nine children. In addition to three sons who died in infancy, they had Elizabeth, George Blake, Anson Stiles, Helen Sherman, Harriet Janet, and Sherman Day, Jr. All three of their sons, George Blake. Anson Stiles, and Sherman Day Jr., carried on the family Yale tradition, in 1925, 1927 and 1936 respectively. (George Blake would go on to attend the
Massachusetts Institute of Technology in 1927.) Two of their daughters, Helen Sherman and Harriet Janet, attended
Smith College (1930, 1934). Their eldest child, Elizabeth, graduated from the University of California in 1920. Thacher was 69 years old when he died, on August 5, 1931, of operative shock. He left behind his wife, three sons, and three daughters. A
Presbyterian, Thacher attended the Ojai Valley Community Church from 1887 until his death. His great-great-grandson, Mateo Thacher, graduated in June 2020, and served as the Thacher School Chair (or head of the student body). == References ==