Onslow soon found itself on the frontiers of the Confederacy, as the White Oak River separated it from the Union forces of the Department of North Carolina headquartered in New Bern to the north and the Confederate forces of the Department of the Cape Fear headquartered in Wilmington to the south. Onslow County contributed seven companies to the Confederate Army, five infantry and two cavalry, which were assigned to the 3rd, 24th, 35th, 41st and 61st Regiments, North Carolina Troops. Over all, more than 1,000 men enlisted to fight for the Confederacy. Notable soldiers from the Camp Lejeune area included Colonel Edward Fonvielle and Lieutenant Colonel (Dr.) William J. Montfort (after whose family "Montford" Point would be named, although incorrectly spelled) of the 21st State Militia, Captains Solomon Gornto and Edwin H. Rhodes of the 3rd North Carolina, and Captain (Dr.) Edward W. Ward of the 41st North Carolina (3rd North Carolina Cavalry). Except for Rhodes, these men and more than 30 others identified from the Camp Lejeune area are buried in the Montford Point Cemetery.
Onslow County served as a battleground for the entirety of the war, with most of the intense fighting in the Camp Lejeune area centered around Bear Creek, Bear Inlet, and the lower New River. It was no coincidence that this fighting took place near the ocean because it consisted mostly of amphibious raids to destroy local salt works.