Federal ordnance stores arrived on Big Tybee Island on the outer channel of the Savannah River to act in the siege of Fort Pulaski, February 21st, 1862. The building of eleven batteries on Big Tybee by the troops under MG Q. A. Gilmore included sixteen Seacoast Mortars, twelve 13 inch and four 10 inch, these batteries ranged from 3400 yards to 1650 yards for the smaller mortars facing the fort located on Cockspur Island. The army beachmaster in charge of accepting the ordnance from the navy and transporting it to the positions laid out by the engineers was Lt. Horace Porter. He describes the methods of transport of the heavy ordnance as follows:
" The heavy guns were landed by lowering them from the vessels into lighters having a strong decking built across their gunwales. They were towed ashore by row-boats at high tide, often in a heavy surf, and careened by means of a rope from shore, manned by soldiers, until the piece rolled off. At low tide this was dragged above the high-water mark.
For the purpose of transporting the 13 inch mortars, weighing 17,000 pounds, a pair of skids was constructed of timber ten inches square and twenty feet long, held together by three cross pieces, notched on. One end of the skids was lashed close under the axle of a large sling-cart, with the other end resting on the ground. The mortar was rolled up by means of ropes until it reached the middle of the skids and chocked. Another large sling-cart was run over the other end of the skids, which was raised by the screw, forming a temporary four-wheeled wagon. Two hundered and fifty men were required to move it over the difficuld roads by which the batteries were reached."
Manpower for this operation was provided by the 7th Connecticutt Volunteers.On the 9th of April the batteries were ready to fire, with orders to open fire being issued in the afternoon. It soon became appearent that the 13 inch Mortars, "were from some cause practically inefficient", only ten percent of the rounds fired from the great guns falling within the fort.
Fort Pulaski ran up a white flag on 2 P.M. on the afternoon of April 11, 1862, with article of surrender signed that afternoon. 5275 shots were fired from the Federal batteries, with 1732 of that total accounted for by the Mortars.