The brigade saw its first pitched battle rather late, as it fought in the June 27, 1862, Battle of Gaines' Mill during the Seven Days Battles. There it sustained heavy casualties, with most of the 4th New Jersey being captured by Confederate forces. The 4th New Jersey's men were subsequently released in a prisoner exchange and returned to their lines, but they lost the Model 1861 Springfield Rifles they'd been carrying. Since none were available to rearm the regiment, they were issued old .69 caliber smoothbore muskets. It then fought in the Second Bull Run Campaign, where it blundered into the entire Confederate army corps commanded by Major General Stonewall Jackson, and at Crampton's Gap during the Battle of South Mountain, where it redeemed its honor by making a triumphant charge up the hill. The 4th New Jersey managed to reequip itself with .58 caliber rifles dropped by the Confederates. Later engagements included Fredericksburg, Chancellorsville, Gettysburg, the Wilderness, Spotsylvania, Cold Harbor, Strasburg, Fisher's Hill, and Cedar Creek.