| Unit Name: | 70th New York Infantry Regiment |
| Dates: | June 1861 - July 1, 1864 |
| Country: | United States of America |
| Branch: | Union Army (Excelsior Brigade) |
| Type: | Infantry |
| Size: | 1,100 |
| Nickname: | "First Excelsior Regiment" |
| Battles: | American Civil War
|
| Commander1: | J. Egbert Farnum |
| Commander1 Label: | Colonel |
| Commander2: | William Dwight Jr. |
| Commander2 Label: | Lieutenant Colonel |
| Identification Symbol Label: | 2nd Division, III Corps |
| Identification Symbol 2 Label: | 4th Division, II Corps |
| Identification Symbol 3 Label: | 3rd Division, II Corps |
The 70th New York Infantry Regiment was one of five infantry regiments formed by former U.S. Congressman Daniel Sickles and established as part of the Excelsior Brigade which fought with the Union Army during multiple key engagements of the American Civil War, including the Chancellorsville, Gettysburg and Overland campaigns. Leaders from the 70th New York recruited men from New Jersey, as well as from cities and small towns across the State of New York.
The regiment was organized in New York City in May 1861 under the authority of the War Department as the 1st Regiment, Sickles' Brigade, at Camp Scott on Staten Island. It mustered into service on June 20, 1861. The 70th left the state for Washington, D.C., on July 23, 1861. It was subsequently attached to Sickles' Brigade, Division of the Potomac, until October, 1861. Then, it was reassigned to Sickles' Brigade, Hooker's Division, Army of the Potomac, until March 1862. (It was formally designated as the 70th Regiment New York Infantry on December 11, 1861.) The 70th was part of the 2nd Brigade, 2nd Division, Third Army Corps, Army of the Potomac, until March 1864. Then it was in the 2nd Brigade, 4th Division, Second Army Corps until May 1864. It finished the war in the 4th Brigade, 3rd Division, Second Army Corps, until July 1864.
Ordered to New York for muster out June 22, 1864. Veterans and Recruits were transferred to the 86th New York Infantry. The 70th mustered out on July 7, 1864, to date from July 1, 1864, after the expiration of its three-year term of enlistment.
The regiment lost during service 9 officers and 181 enlisted men killed and mortally wounded, and 2 officers and 62 enlisted men by disease for a total of 254 fatalities.