The following is taken from New York in the War of the Rebellion, 3rd ed. Frederick Phisterer. Albany: J. B. Lyon Company, 1912. 

This regiment, Col. Timothy Sullivan, was accepted by the State May 17, 1861, organized at Elmira, and there mustered in the service of the United States, for two years, July 2, 1861, to date from May 17, 1861. Its three years' men were, in May, 1863, transferred to the 76th N. Y. Volunteers.
The companies were recruited principally: A, B, C, F and I at Oswego; D at Parish; E and H at Fulton; G at Sandy Creek; and K at Belleville; the men were from Oswego county, except those of Company K, who were from Jefferson county.
The regiment left the State July 2, 1861; served at or near Washington, D. C., from July 3, 1861; in Keyes' Brigade, Division of Potomac, from August 4, 1861; in same brigade, McDowell's Division, Army of the Potomac, from October 15, 1861; in Augur's Brigade, same division, from January, 1862; in 1st Brigade, 3d, King's, Division, 1st Corps, Army of the Potomac, from March, 1862; in same brigade and division, Department of Rappa-hannock, Va., from May, 1862; in 1st Brigade, 1st Division, 3d Corps, Army of Virginia, from June 26, 1862; in the 1st Brigade, 1st Division, 1st Corps, Army of the Potomac, from September 12, 1862; and it was honorably discharged and mustered out, under Col. Samuel ,R. Beardsley, May 29, 1863, at Elmira.
Colonel Wm. C. Raulston received authority, August 25, 1863, to reorganize the regiment for three years' service; September 25, 1863, the authority was modified to reorganize it as the 24th Regiment, N. Y. Volunteer Cavalry.
During its service the regiment lost by death, killed in action, 5 officers, 63 enlisted men; of wounds received in action, 1 officer, 22 enlisted men; of disease and other causes, I officer, 30 enlisted men; total, 7 officers, 115 enlisted men; aggregate, 122; of whom 2 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.

Twenty-fourth Infantry.—Cols., Timothy Sullivan, Samuel R. Beardsley; Lieut.-Cols., Samuel R. Beardsley, Robert Oliver, Jr.; Majs., Jonathan Tarbell, Andrew J. Barney, Robert Oliver, Jr., Melzer Richards. The 24th, the Oswego County regiment, contained nine companies from .Oswego county and one from Jeffer-1 son. It was mustered into the U. S. service for a two years' term, July 2, 1861, at Elmira, and left for Washington the same day. It first encamped on Meridian hill, but moved to Arlington mills on July 22, and late in September established winter quarters at Upton's hill. The regiment was first assigned to Keyes' brigade, which became on Oct. I, the 1st brigade, 1st division, and on March 13, 1862, the 1st brigade, 1st division, 1st corps,—the "Iron Brigade." In March, 1862, the brigade moved to Centerville, but returned at once to Alexandria, and in April proceeded to Bristoe Station and thence to Fredericksburg. During June and July it encamped at Falmouth after a sharp encounter with the enemy at that point in April. It was present during the actions at Rappahannock Station and Groveton and in the second battle of Bull Run lost 237 merriT bers in killed, wounded and missing. After a brief rest at Upton's hill, the brigade was again active at South mountain and Antietam, after which it went into camp at Sharpsburg until late in the autumn, when it moved to Fredericksburg, participated in the battle there, and then established winter quarters at Belle Plain. In the Chancellorsville movement the brigade was held in reserve and on May 29, 1863, the 24th was mustered out at Elmira, having lost 91 men by death from wounds and 31 by death from other causes.