He received the Medal of Honor for his service in the American Civil War in 1872 but it was rescinded in 1917 when supporting documentation was not found.

As a Judge Advocate in the United States Army, he prosecuted the case of Johnson Chesnut Whittaker, a black cadet at West Point.

He was elected New York County District Attorney in 1897, but was put on trial for corruption, and despite acquittal, was removed from office by Theodore Roosevelt in 1900.

He refused to prosecute the corrupt Tammany Hall bosses of New York City, proclaiming "The hell with reform!"

Shortly after the outbreak of the American Civil War, Gardiner was commissioned as a first lieutenant in the 31st New York Infantry Regiment on May 27, 1861, and was mustered out of service on August 7, 1861.

He was again commissioned a captain in the same regiment when it was reactivated on June 18, 1863, due to the movement of Lee's Army of Northern Virginia towards Pennsylvania.

[5] For his actions at the Battle of Sporting Hill Gardiner received the Medal of Honor on September 23, 1872, for "distinguished service performed during the war while serving as Captain 22nd New York State Militia".

[2] Gardiner's award of the Medal of Honor was rescinded in early 1917 after a review panel, led by retired Lieutenant General Nelson A.

He transferred to the 1st Artillery Regiment on April 3, 1869, and served for a time as aide-de-camp to Major General Irvin McDowell who was commander of the Department of the East with its headquarters on Governors Island in New York Harbor.

Gardiner was promoted to the rank of major on August 18, 1873, and served as a Judge Advocate for 15 years until he retired from the Army on December 8, 1888.

Gardiner initiated the entire law curriculum, including study of the Lieber Code and a textbook he himself wrote.

[12] In 1878, a commission reviewed the court-martial of Major General Fitz John Porter, who had been dismissed from the Army in 1863 for his actions at the battle of Second Bull Run.

The commission chairman, General John M. Schofield, appointed Gardiner as recorder, but he "took upon himself the role of a judge advocate in a court-martial," contesting evidence favorable to Porter.

[18] In 1887 Gardiner was appointed Acting Assistant Secretary of War and held the position until he retired from the Army on December 8, 1888, for "disability in the line of duty".

[21] Gardiner was allied with Tammany Hall boss Richard Croker and, in November 1897, was elected on the Democratic ticket as New York County District Attorney.

In September 1899, Gardiner appointed Columbia Law School alumnus James Dickson Carr to serve as the first African American assistant district attorney in New York state history.

[22] In December 1900 formal charges were brought against Gardiner for "interfering with deputies of the Attorney General in presentation of election cases to the Grand Jury and the prosecution thereof".

[21] Among the beneficiaries of Gardiner's anti-reform attitude was saloonkeeper Frank J. Farrell, who is said to have opened three hundred pool halls (in reality fronts for bookmakers) after his friend took office, building a fortune that he would use to bring the New York Yankees to town in 1903.

Through his efforts to recruit new members, define policies and establish administrative procedures, he was probably the single person most responsible for the rejuvenation for the Society of the Cincinnati in the late 19th century.

[citation needed] Gardiner was highly involved in the planning for the dedication of a statue of the French nobleman Rochambeau in Lafayette Square in Washington, D.C., on May 24, 1902.

The ceremony involved an official delegation from France, senior officers the United States Army and Navy, as well as the Society of the Cincinnati.

Gardiner's son Philip served as a major in the Army Judge Advocate General Corps during the First World War.

Asa Bird Gardiner died of a stroke of apoplexy at his home, Orrell Manor, in Suffern, New York, on May 24, 1919, at the age of 79.