The following is taken from New York in the War of the Rebellion, 3rd ed. Frederick Phisterer. Albany: J. B. Lyon Company, 1912. 
August 8, 1862, Col. John E. McMahon received authority to recruit, with headquarters at Buffalo, the 3d Regiment of the Corcoran Brigade. October 7, 1862, this regiment was ordered to Staten Island. The Phoenix or the 4th Regiment of the Empire Brigade, recruited by Col. James C. Burke, under authority dated July 23, 1862, was assigned to the Corcoran Brigade September 22, 1862, as the 7th Regiment of this brigade. At the reorganization of the Corcoran Brigade, November 17, 1862, the 164th Regiment was formed, with John E. McMahon as Colonel, by the consolidation of the 7th with the 3d, and the men recruited for the 8th Regiment, and by transferring original Companies A and D of the 3d Regiment to the 155th Infantry. The reconstructed regiment was mustered in the service of the United States for three years at Newport News, Va., November 19, 1862.
The companies were recruited principally: A at Potsdam, Canton, Malone, Oswe-gatchie and Pierrepont; B at Lockport, Newfane, Rochester, Ridgway and Buffalo; C and D at Buffalo; E, F and K at New York city and Brooklyn; G and I at New York city, Brooklyn and Greenburg; and H at New York city, Brooklyn, Utica, New Hartford and Newport.
The regiment left the State November 6, 1862; it served in the Department of Virginia, at Newport News, Va., from November, 1862; at Suffolk, Va., in Corcoran's
Brigade, Peck's Division, from December, 1862; in Corcoran's, later Murphy's, Brigade, Peck's, later Corcoran's, Division, 7th Corps, from January, 1863; in the 1st Brigade, King's Division, 22d Corps, from July 16, 1863; in 2d Brigade, Tyler's Division, 22d Corps, from January, 1864; in 4th Brigade, 2d Division, 2d Corps, from May 17, 1864; in 2d Brigade, 2d Division, 2d Corps, from June 26, 1864; and, commanded by Col. Wm. DeLacy, it was honorably discharged and mustered out July 15, 1865, near Washington, D.C.
During its service the regiment lost by death, killed in action, 5 officers, 61 enlisted men; of wounds received in action, 5 officers, 46 enlisted men; of disease and other causes, 4 officers, 127 enlisted men; total, 14 officers, 234 enlisted men; aggregate, 248; of whom 2 officers, 84 enlisted men, died in the hands of the enemy.

The following is taken from The Union army: a history of military affairs in the loyal states, 1861-65 -- records of the regiments in the Union army -- cyclopedia of battles -- memoirs of commanders and soldiers. Madison, WI: Federal Pub. Co., 1908. volume II. 
One Hundred and Sixty-fourth Infantry.—Cols., John E. McMa-hon, James P. McMahon, William DeLacey; Lieut.-Cols., James C. Burke, William DeLacey, John Beattie; Majs., Michael D. Smith, John Beattie, Bernard O'Reilly. This was one of the four regiments forming the brigade of Irish soldiers known as the Corcoran Legion. The 164th was recruited in New York, Brooklyn, Buffalo, and the counties of Niagara and St. Lawrence, and was mustered into the U. S. service at Newport News, Va., Nov. 19, 1862, for three years. Col. John E. McMahon was one of three brothers, all of whom became colonels. He succumbed to disease in March, 1863, and was succeeded by his brother, James P. McMahon, who was killed in action at Cold Harbor. Lieut.-Col. DeLacey had formerly rendered gallant service as major of the 37th N. Y. He was wounded several times and rose to the rank of brevet brigadier-general. Col. Fox, in his account of this splendid fighting regiment, says: "The Legion was ordered to the Peninsula soon after, where it was placed in the 7th corps. On Jan. 29, 1863, the brigade started on the Blackwater expedition (Gen. Corcoran commanding the division), during which it saw its first fighting, at the affair known as the Deserted House. The gallant behavior of the Legion in this engagement elicited a general order from department headquarters which was highly complimentary to the command. In April, 1863, it was actively engaged in the siege of Suffolk. Gen. Corcoran commanded the Legion up to the time of his death, which occurred at Fairfax, Va., Dec. 22, 1863. From July, 1863, until May, 1864, the Legion was stationed near Washington, after which it joined Grant's army at Spottsylvania, where it was assigned to Gibbon's (2nd) division, 2nd corps. At Cold Harbor it was in the assaulting column, and succeeded in carrying the portion of the enemy's works in its immediate front, but with a heavy loss in men and officers. Seven officers of the regiment were killed in that assault, including Col. McMahon, who was shot down after having with his own hands planted the regimental colors on the Confederate works. The regiment, however, was obliged to fall back, owing to the failure at other points of the line, having lost 16 killed, 59 wounded and 82 missing. The Legion was commanded at Spottsylvania by Col. Murphy (182nd N. Y.), who afterwards fell mortally wounded at Dabney's mill. The casualties in the regiment at Spottsylvania were 12 killed, 66 wounded and 44 missing." The regiment suffered severely in the first assaults at Petersburg, where its losses amounted to 63 killed and wounded, chiefly incurred during the assault of June 16. It was present at Deep Bottom and Strawberry Plains, and was again hotly engaged at Reams' station with a loss of 9 killed and mortally wounded, I wounded, 9 officers and 98 men missing or captured. From June 26, 1864, until the close of the war, the Legion, together with the 8th N. Y. heavy artillery, made up the 2nd brigade, 2nd division, 2nd corps. It was in the action on the Boydton road,, losing 7 men; at Hatcher's run in December, and closed its active service with the Appomattox campaign in 1865, fighting at White Oak ridge, fall of Petersburg, High bridge, Farmville and Appomattox. It was mustered out near Washington, under Col. DeLa-cey, July 15, 1865. The total enrollment of the regiment was 928, of whom 10 officers and 106 men—or 12.5 per cent.—were killed and mortally wounded; 3 officers and 126 men died of disease and other causes; total deaths, 245, of whom 2 officers and 84 men died in the hands of the enemy.