Per his widow's pension papers, d'Estimauville enlisted on 23 November 1861 and served as a captain's clerk on the U.S.S. Flambeau.
On 31 January 1863, LCDR J. H. Upshur of the Flambeau send ashore on Bull's Island, SC, a foraging party consisting of Acting Master William B. Sheldon, Acting 1st Assistant Engineer Albert G. Pemble, d'Estimauville and an unnamed black sailor. Premble and d'Estimauville approached the slaving dwellings of a plantation known as Gibbes' Farm, when eleven Confederates in uniform came out of the house. d'Estimauville, beleving that the party was in danger of being captured, proposed to flee, but Pemble decided to hide in some bushes instead and was captured. d'Estimauville ran, managing to elude capture and returned to his vessel. Sheldon and the unnamed sailor also approached the plantation with the same result. Sheldon was captured and the sailor ran, managaging to return to the Flambeau. The next morning, hoping to find his missing officers, Upshur sent a search party ashore under the command of Lt. Smith and including d'Estimauville and Acting Ensign Gardener Cottrell as part of the search party. While searching the island for the missing officers, Cottrell was shot twice by Confederates and Alexander Cushman, captain of the foretop was killed. Lt. Smith was forced to withdraw the search party out of caution. Sheldon was released at some point from the prison at Columbia, SC and records show he was eventually given command of his own vessel, the U.S.S. Shokokon. As for Pemble, records show that he deserted from the Navy on 28 February 1863 and enlisted on the Confederate side to serve as a machinist in the Macon, GA arsenal.
d'Estimauville was appointed an Acting Ensign on 24 June 1863 from the state of Pennsylvania while still attached to the Flambeau.
Per United States Service Magazine, he was detached from the Flambeau and ordered to the U.S.S. Tecumseh on 15 February 1864 along with Acting Ensigns Gardner Cottrell and Joseph P. Gallagher. He checked in on 26 February 1864 per the letter he sent to SECNAV Welles acknowledging his orders.
While the Tecumseh was fitting out in New York, d'Estimauville fell ill for the first time and a med board was held for him, finding that while he suffered from "catarrh and some derangement of the liver and bowels contracted according to his statement in the line of duty on board the Tecumseh" that he was fit for duty.
The July 1864 issue of United States Service Magazine reports that d'Estimauville was detached from the Tecumseh and ordered to the U.S.S. Otesgo on 2 May 1864.
In early October 1864, d'Estimauville was condemned by medical survey due to suffering from dysentery and ordered to report to the Norfolk Naval Hospital. However d'Estimauville, "owing to the sanitary condition of the [Albemarle] Sound and the difficulty of communication with Norfolk" was unable to get to Norfolk and went to New York instead. He arrived at his father's residence in the city in early November 1864, and wrote a letter to Gideon Welles explaining why and requesting that his illness be treated at Naval Hospital New York instead. Welles ordered him to Norfolk to be treated there, but d'Estimauville's father had to reply on his behalf explaining that he was paralyzed, but will try to obey Welles' orders anyway. d'Estimauville was admitted to Naval Hospital New York on 17 December 1864 on orders of Welles. Three days later, his only daughter, Frederica Rebecca Jeanne was born in Philadelphia.
Over the next few weeks, d'Estimauville slowly recovered from his paralysis that was suspected to be caused by malaria he contracted in Albemarle Sound. His medical ticket notes that on 9 February 1865, he was able to raise his hands to his head. On 19 February, he was noted to have a swollen throat. Fearing that death was close, he asked to be discharged to his parents home presumably to see his wife and newborn daughter, but was refused with the surgeon in charge of his case telling him per his wife's statement that "he might as well die in the hospital as anywhere else."
On 23 February, d'Estimauville talked one of the surgeon's stewards into obtaining him a carriage to take him to his parent's house in Brooklyn. Before he was able to depart the hospital grounds, he was pulled out of the carriage gasping for breath and died in the arms of one of the stewards helping him before they could get him back into the building.
IntermentGreen-Wood Cemetery, Brooklyn, NY. Lot 8333, Section 72.
DependentsRebecca N. (wife), Married 15 March 1864
Frederica Rebecca Jeanne (daughter), Born 20 December 1864
Awards & Memorials
Alternate Spellings of NameFrederick H. d'Estimanville
Frederic Henri d'Estimauville
References and SourcesBaptêmes non catholiques de la région de Montréal, 1766-1835. Bibliothèque et Archives Nationales du Québec
 Roy, Pierre Georges La Famille d'Estimauville de Beaumouchel (Lévis, Quebec, Canada, 1903)
"Report of Lieutenant-Commander Upshur, U.S. Navy, commanding U.S.S. Flambeau" Official Records of the Union and Confederate Navies in the War of the Rebellion: Series I, Volume 13 South Atlantic Blockading Squadron from May 14, 1862 to April 7, 1863 (1901)
 Case Files of Approved Pension Applications of Widows and Other Dependents of Civil War and Later Navy Veterans ("Navy Widows' Certificates"), 1861-1910
Various letters from F. H. d'Estimauville. M148, Letters Received by the Secretary of the Navy From Commissioned Officers Below the Rank of Commander and From Warrant Officers ("Officers' Letters"), 1802–1884; National Archives, Washington, D.C.