Each battery had a service magazine capable of containing a supply of powder for about two days' firing. A depot powder magazine of 3,600 barrels' capacity was constructed near the Martello Tower, which was the landing place for all the supplies. Serious difficulties were encountered in making a road sufficiently firm to serve for this heavy transportation.

Tybee Island is mostly a mud marsh, like other marsh islands on this coast. Several ridges and hummocks of firm ground, however, exist upon it, and the shore of Tybee Roads, where the batteries were located, is partially skirted by low sand banks, formed by the gradual and protracted action of the wind and tides. The distance along this shore from the landing place to the advanced batteries is about 2 1/2 miles. The last mile of this route, on which the seven most advanced batteries were placed, is low and marshy, lies in full view of Fort Pulaski, and is within effective range of its guns. The construction of a causeway resting on fascines and brush-wood over this swampy portion of the line; the erection of the several batteries, with the magazines, gun platforms, and splinter-proof shelters; the transportation of the heaviest ordnance in our service by the labor of men alone; the hauling of ordnance stores and engineer supplies, and the mounting of the guns and mortars on their carriages and beds had to be done almost exclusively at night, alike regardless of the inclemency of the weather and of the miasma from the swamps.

No one except an eye-witness can form any but a faint conception of the herculean labor by which mortars of 8 1/2 tons' weight and columbiads but a trifle lighter were moved in the dead of night over a narrow causeway, bordered by swamps on either side, and liable at any moment to be overturned and buried in the mud beyond reach. The stratum of mud is about 12 feet deep, and on several occasions the heaviest pieces, particularly the mortars, became detached from the sling-carts, and were with great difficulty, by the use of planks and skids, kept from sinking to the bottom. Two hundred and fifty men were barely sufficient to move a single piece on sling-carts. The men were not allowed to speak above a whisper, and were guided by the notes of a whistle.

The positions selected for the five most advanced batteries were artificially screened from view from the fort by a gradual and almost imperceptible change, made little by little every night, in the condition and appearance of the brush-wood and bushes in front of them. No sudden alteration of the outline of the landscape was permitted. After the concealment was once perfected to such a degree as to afford a good and safe parapet behind it less care was taken, and some of the work in the batteries requiring mechanical skill was done in the daytime, the fatigue parties going to their labor before break of day and returning in the evening after dark. In all the batteries traverses were placed between the pieces. With two exceptions (Batteries Lincoln and Totten) the magazines were placed in or near the center of the battery, against the epaulement, with the opening to the rear. An ante-room for filling cartridge bags was attached to each. The magazines for the Batteries Lincoln and Totten were located in the rear of the platforms.

For rivetting the sides of the traverses and epaulements fascines, hurdles, brush, and marsh sods were used. Marsh sods form the best revetment for sandy soil. All the others allow the sand to sift through them to such an extent as to become a serious annoyance to the men serving the pieces.

In order to diminish as much as possible the labor of forming the parapets in front of the pieces the foundation timbers of all the gun