On September 11, 1859, William was married to Lillius Gilchrist (1839–1922), the daughter of George W. Gilchrist, a prominent ship builder of
Thomaston, Maine, and Mary Jane (née Smalley) Gilchrest. Together, William and Lillius had eleven children, including: • Alice Gertrude Grace (born in South America, June 11, 1860), who married the New York architect
Albert D'Oench in 1901. • Florence F. Grace (born in South America, September 20, 1861; died September 27, 1861). • Lilius Clemintina Grace (born in South America, October 24, 1864; died in Ireland, June 26, 1866). • Agnes Isadora Grace (born in Brooklyn, N.Y., April 4, 1867; died in New York City, March 8, 1884). • Mary Augusta Grace (born in Brooklyn, September 2, 1868; died there February 16, 1870). • Lilius Annie Grace (born in Brooklyn, September 1, 1870; died there August 30, 1871). •
Joseph Peter Grace (born at
Great Neck, N.Y., June 29, 1872; died there July 15, 1950). • Lilias Juanita Grace (born in New York City, March 30, 1874), who married George Edward Kent on July 12, 1898. • Louise Natalie Grace (born in New York City, December 23, 1875; died in North Hills, Long Island, New York in 1954). • William Russell Grace, Jr. (born April 11, 1878; died in
Aiken, South Carolina, March 31, 1943). • Caroline S. Grace (born April 22, 1879; died April 21, 1882). Grace died on March 21, 1904, at his residence, 31
East 79th Street, in
New York City. His funeral was held at the
Church of St. Francis Xavier on West 16th Street and he was buried at the
Holy Cross Cemetery in Brooklyn. His estate was valued at $25,000,000. ==See also==