Overall, the regiment lost 5 officers and 156 enlisted men killed or mortally wounded and 2 officers and 103 enlisted men to disease during the Civil War.
The regiment's first commander, Colonel James H. Simpson, helped lead the 4th N.J through the hardships of the first year of campaigning.
It was attached to Runyon's New Jersey Brigade, Defenses of Washington, to June 1861.
It was then attached to 1st Brigade, Runyon's Reserve Division, McDowell's Army of Northeast Virginia.
The 4th New Jersey Infantry was reorganized at Camp Olden in Trenton for three years service on August 19, 1861, under the command of Colonel James H. Simpson.
The regiment was attached to Kearney's Brigade, Division of the Potomac, to October 1861.
Kearney's Brigade, Franklin's Division, Army of the Potomac, to March 1862.
The regiment was surrounded at Gaines Mill and most of its men taken prisoner.
After the Seven Days Battles, they were freed by the Confederate authorities in a prisoner exchange.
The 4th New Jersey had been armed with M1861 Springfield rifles, however upon returning from captivity, the authorities in Washington had no rifled muskets to rearm the regiment with, thus they were given outdated .69 smoothbore muskets.
The regiment was forced to use them until the Battle of South Mountain in September, when they rearmed themselves with Enfield rifles dropped by retreating Confederates.
Reconnaissance to East Branch Chickahominy June 7 (Companies D, F, and I).
In camp near Warrenton, Va., until September 15, and at Culpeper Court House until October.
Repulse of Early's attack on Fort Stevens and the northern Defenses of Washington July 11–12.
Battle of Cedar Creek October 19, Duty in the Shenandoah Valley until December.
The 4th New Jersey Infantry mustered out of service July 9, 1865 at Hall's Hill, Virginia.
The 4th New Jersey Volunteer Infantry portrays the group at many reenactments.
They also do fundraiser events and living histories in various parks and battlefields.