William Endicott was born in Salem, Massachusetts, in November 1826, to a prominent family with deep colonial roots. He remained in the area for his schooling, studying at Harvard College and graduating Harvard Law School in 1850. He then established his own law practice in Essex County, Massachusetts, in 1853 and became a prominent litigator.

Originally a Whig, Endicott turned to the Democratic Party in 1856. He suffered several electoral defeats running for both state attorney general and Congress after the Civil War. When Massachusetts expanded its supreme court, Endicott was named to one of the new seats in 1873; he served on the high court for nine years.

Endicott resigned in 1882, citing ill health, and returned to public life three years later as Grover Cleveland’s secretary of war. In that capacity, Endicott oversaw the internal reform of the military and expansion of American coastal defenses. The Endicott Board of Fortifications, created by Congress in March 1885, recommended a major improvement program for the modernization of port defenses along the Eastern seaboard and Great Lakes.

After serving in Cleveland’s cabinet, Endicott returned to Salem in 1889 and lived off his and his wife’s personal fortunes.