Because of the length of the coastline of the United States, from the beginning American ordnance and engineers placed an emphasis on heavy artillery mounted in coastal defences. The Union army organised its 'Heavy Artillery' into separate regiments, uniformed and equipped differently. While the Field Artillery was assigned across the fighting fronts Heavy Artillery units served the big guns in the forts and the defences of Washington. The Confederates did not differentiate types of artillery and those that became known as Heavy Artillery did so through informal association rather than formal designation. This book details the development and usage of the big guns.
American Civil War Artillery 1861-65 (2) by Philip Katcher