Ambrose William Burt was born in England, migrated to Victoria, Australia and made his home in Melbourne. He was living there when the "CSS Shenandoah", a Confederate Cruiser during the American Civil War, arrived in Port Phillip Bay off Melbourne on January 25, 1865. Some twenty days later, in February, Ambrose like many others living in the area joined the thousands to go down and see the Confederate warship; but Ambrose secretly went aboard the "CSS Shenandoah" in violation of the Victorian mandate not to do so, on the night of February 17, 1865.

Wanting to join the crew, Ambrose hid himself so not to be found, until the "Shenandoah" had returned to sea, leaving Australian waters. On February 18, 1865, after the ship was well into international waters, Ambrose came out of hiding and even though he had no experience at sea, he joined forty-one others and signed aboard the "Shenandoah" as a landsman; the lowest rank of the United States Navy, performing menial, unskilled work aboard ship. By placing his mark beside his name for the pay of $16.00 he became a crewmember. William A. Temple in his affidavit, however, incorrectly recorded Ambrose's first name as ‘Ernest'. Likewise, the Official Records of the War of the Rebellion also made a mistake, and recorded his last name as being ‘Boit'.

Ambrose was later promoted to the rank of Petty Officer, served as a surgeon's steward and was one of the signatories who expressed confidence in the command of Lieutenant James I. Waddell, in a petition dated September 1865; remaining aboard the "Shenandoah" until the end of her epic voyage. With the surrender of the "CSS Shenandoah" by Lieutenant James I. Waddell, on November 6, 1865 to British Captain Paynter commanding Her Majesty's ship "Donegal, at Liverpool, England, Ambrose accompanied all the crew as they disembarked and was given quarters ashore.