The following is taken from New York in the War of the Rebellion, 3rd ed. Frederick Phisterer. Albany: J. B. Lyon Company, 1912. 
September 18, 1862, the offer of service of the 19th Regiment of the National Guard was accepted by the Governor of the State, and Col. Wm. R. Brown authorized to recruit his regiment to full numbers and for a service of nine months; it was designated the 168th Regiment of Volunteers, organized at Newburgh, and there mustered in the service of the United States January 23d, Company K, however, not until February 11, 1863.
The companies were recruited principally: A at Wallkill, Montgomery, Mount Hope, Lisle, Coventry and New York city; B at Newburgh, Walden and Fishkill; C, D — Washington Continentals — and I at Newburgh; E at Peekskill, Newburgh and Yorktown; F — Newburgh Guard — at Newburgh, Fishkill, Poughkeepsie and New York city; G at Newburgh, Crawford and Rondout; H at Goshen, Bainbridge, Union, Greene, Binghamton, Lisle and Fishkill; and K at at Fishkill, Montgomery, Poughkeepsie and New York city.
The regiment left the State February 12, 1863; it served at Yorktown, Va., in Bus-teed's Brigade, 1st Division, 4th Corps, from February, 1863; in King's Brigade, 1st Division, 4th Corps, from April, 1863; in the 22d Corps, from June, 1863; in the 2d Brigade, 2d Division, nth Corps, from July, 1863; and, commanded by Colonel Brown, it was honorably discharged and mustered out October 31, 1863, at Newburgh, N. Y.
During its service the regiment lost by death, killed in action, I enlisted man; of disease and other causes, 1 officer, 36 enlisted men; total, 1 officer, 37 enlisted men; aggregate, 38.

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-eighth Infantry.—Col., William R. Brown; Lieut.-Cols., James Low, James C. Rennison; Majs., George Walter, James C. Rennison, Daniel Torbush. The 168th, the 19th militia, was a nine months regiment from Newburg. On Sept. 18 1862, Col. Brown tendered the governor of the state the service the19th militia and was authorized to recruit the same to standard requirement for a service of nine months. It was mustered in the U. S. service on Jan. 23, 1863, with the exception of Co. ] which was mustered in on Feb. 11, 1863, and left the state Feb. 1, 1863, for Yorktown, Va.,. and was assigned to Busteed's brigade 1st division, 4th corps. Subsequently it served in King's brigade same division and corps until June, when it was assigned to the 22nd corps, and the following month was placed in the 2nd brigade 2nd division, 11th corps. It took part in a skirmish at Walkerto Va., in May, again skirmished there during the expedition to the place in June, and was engaged in a skirmish at Yorktown June In addition it took part in a number of minor affairs. The regi-ment was mustered out and discharged at Newburg, N. Y. Oct. 31, 1863. Its loss during service was I man killed in action; officer and 36 men died of disease and other causes; total deaths, 38.