Fox was born at Saugus, Massachusetts, and his parents named him after Swedish King Gustav I, also known as Gustav (or Gustavus) Vasa.[1] His parents, Dr. Jesse Fox and Olivia Fox (née Flint) were not Swedish American, and may have been inspired to name their son after Gustav I by Henry Brooke's popular play Gustavus Vasa: The Deliveror Of His Country.[1] Fox attended Lowell High School Lowell, Massachusetts from 1836 to 1838.
At the start of the American Civil War he volunteered for service. President Abraham Lincoln gave him a temporary appointment in the Navy and sent him in the steamer Baltic to the relief of Fort Sumter. Fox could not relieve the fort before Confederate bombardment forced its surrender, but afterwards he brought away the garrison.
On August 1, 1861, Lincoln appointed him Assistant Secretary of the Navy, an office which he held until the close of the Civil War. In 1866, he was sent on a special mission to Russia; he conveyed the congratulations of the President to TsarAlexander II upon his escape from assassination. His voyage was made in the monitorMiantonomoh, which was the first vessel of this class to cross the Atlantic. They were accompanied by Augusta.
In 1882 he published a paper suggesting that Samana Cay in the Bahamas was Guanahani, or San Salvador, the first island Christopher Columbus reached in his discovery of the Americas. Little attention was paid to his paper until 1986, when the National Geographic Society also concluded that Samana Cay was San Salvador.
Fox, Gustavus V. (1882), An Attempt to Solve the Problem of the First Landing Place of Columbus in the New World. Report of the Superintendent of the U. S. Coast and Geodetic Survey (Appendix No. 18, June 1880), Washington: Government Printing Office.