Following the Revolution, veterans of the Delaware Regiment reorganized the volunteer militia and carried on the regimental tradition through separate volunteer companies of light infantry, artillery, and cavalry. These members bought their own uniforms, horses, and even bought their own artillery pieces.

In the War of 1812 all Delaware volunteer units saw service at Lewes, where they comprised the bulk of force that drove off a British naval squadron seeking control of the Delaware River.

In the Mexican War (1846-1847), the Federal Government would not accept volunteer companies but the Delaware volunteers were not content to stay home. After much red tape, a statewide composite unit was formed. They fought with distinction in the battles of Contreras, Cherubusco, Molino del Ray and Chapultepec where there were almost twice as many Delaware volunteers present as marines. The unit lost so many men in these actions it became known as "The Bloody 11th."

At the outbreak of the Civil War, President Lincoln called on the Governor for the detachment of one regiment and Delaware had no common or enrolled militia, only volunteers. Governor Burton, the neutralist governor of a border state, correctly but misleadingly replied to the President that he had no militia. He recommended the formation of additional volunteer companies under state law. Volunteers could now offer their services to fill the state's quota of troops.

One Wilmington volunteer company, the National Guards (198 Artillery) was so anxious for action they didn't wait for the formation of a Delaware unit but volunteered for service with the 24th Pennsylvania Regiment which was ready to leave for the front.

Other volunteer units reestablished the State's regiment - the First Delaware. Honors won by the regiment are proudly carried on their organizational colors.

At Fredericksburg and Chancellorsville, the regiment was cited in official reports for its outstanding performance. Three days into the Battle of Gettysburg the Delawares took the full fury of Confederate Generals Pickett and Pettigrew. Much of the credit belongs to the Delaware regiment for bringing Pickett to a halt at the "high water mark of the Confederacy."

The regiment went through the Wilderness campaign, Spotsylvania, Cold Harbor and the siege of Petersburg. When their three year enlistments expired the two regiments combined into the First Delaware Veteran Volunteer Regiment made up of men who reenlisted "for the duration."