Commander Alexander Slidell MacKenzie
He was born Alexander Slidell and was a brother of John Slidell, Confederate States Diplomatic Agent. He had his name changed to Alexander Slidell MacKenzie in 1838 or 1839 in order to be eligible for an inheritance.
He was appointed a Midshipman in the United States Navy to date from 1 January 1815, and served to 13 September 1848, when he died with the rank of Commander.
His service, in addition to shore duty, included a cruise on board the Frigate Macedonian in the Pacific 1818-21; duty in the West Indies 1824-25; on the Frigate Brandywine in the Gulf of Mexico March-July 1830; and in the Mediterranean from October 1830 to July 1835 on the Flagship Independence and Brig Dolphin, Brazil Squadron 1837-39; Steamer Missouri preparing for her initial trip at New York 1841 to March 1842; USS Somers 1842-43 during a cruise to the coast of Africa (He was ordered to the Somers 7 May 1848.); and Steamer Mississippi, Gulf Squadron 1847-48.
1815 January Appointed Midshipman. Records incomplete. The following is taken from the Navy Registers: 1817 On furlough. 1818 New York. 1819 Frigate Macedonian. 1820 Frigate Macedonian. 1821 July Reported for duty on New York station. 1822 March Ordered from New York to Boston to Macedonian. 1822 August Reported at New York. 1823 April Furloughed six months. 1823 October Furloughed six months. 1824 May Furloughed six months. 1825 January Lieutenant. 1825 July Absent six months. 1825 August Absent six months and to report for duty in Mediterranean Squadron. 1826 January Leave twelve months. 1827 May Sloop Falmouth. 1827 December Order revoked. 1829 December To the Brandywine. 1830 July Leave unlimited. 1830 August To rejoin the Brandywine. 1833 July Leave three months. 1833 September Leave twelve months. 1834 October Leave extended twelve months. 1835 March Leave three months and previous leave revoked &c. 1835 July Leave three months. 1835 October Leave three months. 1837 January For duty in the ship Independence.
(Name altered to Alexander Slidell MacKenzie by an act of the legislature of New York.)
1839 May Leave three months. 1841 September Commissioned a Commander from 8 Septemer 1841. 1841 December For duty in the ship Missouri. 1842 May Detached to command of the Somers. 1843 April Acquitted by Court Martial & w.o. (see Officers' Book No. 34, page 370. 1846 May 16 Ordnance duty. 1846 May 25 Report at Department for special service. 1846 July Detached from special service & w. orders. 1846 September To ordnance duty. 1847 February To ordnance duty - Home Squadron. 147 August To the Mississippi by 15 September. 1848 April Detached from command of the Mississippi and three months leave. 1848 September Died at Tarrytown, New York. (See Captain McKeever's letter of 14th September 1848) (Also letter of Commodore Perry16 September 1848).
Your letter of May 20, requesting information concerning the ancestry of Commander Alexander Slidell MacKenzie has been referred to this office for reply by the Bureau of Navigation.
Particulars as to the parentage, etc., do not form a part of the early records of the Navy Department. Such information, if available at all, is usually obtained from incidental reference in correspondence or from outside sources. I shall be glad to give you what we have, which, however is very little.
The biographical sketch of Alexander Slidell MacKenzie in the recently published Dictionary of American Biography states that he was born April 6, 1803, and that he was the son of John Slidell, a New York merchant, and Margery or May MacKenzie, a native of the Highlands of Scotland, and a brother of John Slidell, the Confederate diplomatic agent. The Navy Department records show that he was warranted Midshipman in the U.S. Navy on January 1, 1817, with a number of other young men, and that his warrant, with those of quite a few others, was delivered that month to "Dr. Marshall". We have not traced the identity of "Dr. Marshall", but it is quite possible that he may have been Surgeon Samuel R. Marshall. The records show also that he was born in and a citizen of the State of New York. He accepted the appointment, apparently in March 1817, but we unfortunately do not have his letter of acceptance. At the time of his appointment and up to May 9, 1817, he was attached to the U.S.S. Java, Captain Oliver H. Perry. He accepted the appointment, apparently in March 1817, but we unfortunately do not have his letter of acceptance. The date of his appointment as Midshipman is given in the navy Registers, 1817-1821, as January 1, 1817, but beginning with 1818 is changed to January 1, 1815.
In searching for a reason for the change of date of appointment from 1817 to 1815 a letter from his father, John Slidell, Esq., to the Navy Department was found, written from New York, October 17, 1817, stating he had just been informed that the U.S. Brig Enterprise, on which his son was then acting as Midshipman, was ordered on foreign service. The letter went on to say that he had been an acting Midshipman for 31 months (which would date the beginning of his service as about March 1815), and had during that time been twice to the Mediterranean, and the last summer attending the survey of the coast; that he was very young, and that he (the father) was desirous that he should perfect himself in French and mathematics, in which studies he was then engaged, and if consistent with the views of the Department he would be highly gratified in his being attached to the U.S.S. Cyane.
The above letter clears up the question of the change of date in his appointment, although we find no letter to either Midshipman Slidell or his father relative to it.
The name of MacKenzie was added to that of Slidell by Act of the Legislature of New York in either 1837 or 1838. We find only two references to this change of name. the first is a letter from him to the Secretary of the Navy, written from the U.S. Brig Dolphin at Rio de Janeiro, Brazil, December 27, 1837, informing him that an application was before the legislature of the State of New York praying that he might be allowed to assume his maternal name of MacKenzie in addition to that of Slidell in order to qualify him to inherit property, and asking that he might be permitted by the Department to be so known in the Navy, and to take the additional name whenever authorized to do so by the legislature. The Second is the Secretary's reply, dated March 13, 1838, informing him that the additional name of MacKenzie had been sanctioned by the Legislature of New York, and he would be known henceforth by the Department as Alexander Slidell MacKenzie.
Commander MacKenzie died suddenly September 13, 1848, at his residence, near Tarrytown, N.Y., of heart disease. The Department was notified of his death on September 14, by Captain Isaac McKeever, Commandant at New York, who stated that he had been informed of it by Commodore Matthew C. Perry.
D. W. Knox
Captain, U.S.N. (RET.),
Officer in Charge.
Mrs. Mabel M.Moran
Source: Adapted from "Commander Alexander Slidell MacKenzie, USN" in ZB Collection, Navy Department Library.
Bibliography - The Somers' Mutiny
Biography - Philip Spencer, Midshipman, USN
Case of the Somer's Mutiny: Defence of Alexander Slidell MacKenzie, Commander of the U.S. Brig Somers... 
Essay on the Legal Aspects of Somers Affair and Bibliography
Extracts from deck log of Somers
Online images of Somers