He served on a major exploring expedition that included both scientific discoveries and controversy, and two historic diplomatic missions.

[4] He befriended young midshipman William Reynolds, whose journals provide a non-official version of the events of the voyage.

[5] In December 1839, the squadron headed farther south, and in January 1840 provided the first sighting of the continent of Antarctica by a US Navy ship.

[citation needed] Wilkes' imperious manner included dismissing many of the officers, leading to further low morale.

After the Peacock was lost in July 1841 while exploring the Pacific Northwest, Guilloû was shuttled between various ships, officially under arrest.

[citation needed] Guilloû filed seven charges against Wilkes, including questioning his claim to have "discovered" Antarctica.

When returning via Honolulu, at the outbreak of the Mexican–American War, the Columbus was recalled to Monterey, California and the ranch of William A. Richardson.

[citation needed] On July 30, 1849, while at Gaeta, the multilingual Guilloû acted as interpreter for a visit to the palace of King Ferdinand II by local diplomat John Rowan.

[2][12] The grateful pope delivered rosaries to the Catholics on the ship; Guilloû received inscribed prayerbooks and a medallion, along with a plenary indulgence.

[14] Active in Freemasonry, he helped reactivate Lodge Le Progrés de l'Océanie in Honolulu that had been chartered from the French organization.

[16] He evidently decided to stick to medicine, since in 1856, he was one of the founding members of the Hawaiian Medical Society, with other prominent doctors such as Gerrit P. Judd and Thomas Charles Byde Rooke.

[20] James W. Borden, the new United States Minister to Hawaii, published letters in the Pacific Commercial Advertiser newspaper of Henry Martyn Whitney with accusations against Guilloû and Abner Pratt, the American Consul who replaced Ogden.

[citation needed] Pratt had already headed back to Marshall, Michigan where he built a majestic mansion, while the Levant was lost at sea.

[citation needed] Although Pratt was asked to return the funds, the American Civil War caused the government to never pursue the case.

Guilloû was one of many physicians called in to help, but they could do nothing and the young prince died, leading to a series of succession crises.

[22][23] Grandson Charles Thomas Blackmore was born July 3, 1888, joined the British army in World War I, and died on June 16, 1915, in the Battle of Bellewaarde.