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. John E. Bendix, was accepted by the State, April 26, 1861; organized at New York city, and there mustered in, the service of the United States for two years, April 23, 1861. Company I was recruited at Brooklyn, the others in New York city.
The regiment left the State, May 24, 1861; served at Newport News, Va., from May, 1861; in the 1st Brigade, 1st Division, Department of Virginia, from March, 1862; and in the 1st Brigade, 1st Division, 2d Corps, Army of the Potomac, from May, 1862. April 23, 1863, the three years' men were attached to the 52d Infantry but not absorbed by them until after the battle of Gettysburg; July 22, 1864, they, but a few men then, were transferred to the 7th Veteran Volunteers. Commanded by Col. George W. Von Schack, the regiment was honorably discharged and mustered out, May 8, 1863, at New York city.
During its service it lost by death, killed in action, 9 officers, 76 enlisted men; of wounds received in action, 5 officers, 34 enlisted men; of disease and other causes, 1 officer, 60 enlisted men; total, 15 officers, 170 enlisted men; aggregate, 185; of whom 7 enlisted men died in the hands of the enemy.

Reorganizing

Colonel George W. Von Schack received, May 6, 1863, authority to reorganize, for a period of three years, his old regiment, the 7th, then about to be mustered out by reason of the expiration of its term of service.
This reorganization was, however, discontinued and the men enlisted transferred, October 14, 1863, to the 178th Infantry. 
To effect the reorganization the following were appointed by the Governor, May 6, 1863, but not commissioned:
George W. Von Schack - Colonel
Frederick A. H. Gaebel - Lieutenant-Colonel
Charles Brestel - Major
Peter Hesse - Adjutant
F. C. G. Moyne - Quatermaster
Charles Gray - Surgeon
These appointments became void on the discontinuance of the reorginization, Ocotober 14, 1863.

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.

Seventh Infantry.—Cols., John E. Bendix, Edward Kapff, George W. Von Schack; Lieut.-Cols., Edward Kapff, Casper Keller, Frederick A. H. Gaebel, Anton Pokomey; Majs., Casper Keller, George W. Von Schack, Frederick A. H. Gaebel, Charles Brestel, Gustavus Seidel, Jacob Scheu. The 7th, the "Steuben Rangers'," was recruited in New York city, except Co. I from Brooklyn, and mustered into the U. S. service April 23, 1861, for a two years' term. It left New York for Fortress Monroe on May 24, and was quartered at Newport News. It took part in the engagement at Big Bethel and returned to camp at Newport News until in March, 1862, when it was assigned to the 1st brigade, 1st division, Army of Virginia. In May it was transferred to the 1st brigade, 1st division, 2nd corps, Army of the Potomac, with which it served through the campaign on the Peninsula, taking part in the Seven Days' battles with heavy loss. At Antietam it lost 15 killed and 49 wounded, but its heaviest loss was at Fredericksburg, when 243 members were killed or wounded out of a total of 488 engaged. On April 25, 1863, the original two years' members were mustered out at New York city and the three years men were transferred to the 52nd N. Y. The 7th was active in the Chancellorsville campaign and at Gettysburg, after which the remnant of the 52nd and the 7th was consolidated with the 7th N. Y. veteran infantry. During the two years' campaign, the loss by death from wounds was 102 and 47 members died from other causes.