Quincy A. Gillmore to W. L. M. Burger, April 9, 1869

No. 17. Tybee Island, Ga., April 9, 1869.

The batteries established against Fort Pulaski will be manned and ready for service at break of day to-morrow. The signal to begin the action will be one gun from the right mortar of Battery Halleck (2,400 yards from the work), fired under the direction of Lieut. Horace Porter, chief of ordnance. Charge of mortar, 11 pounds; charge of shell, 11 pounds; elevation, 55 degrees; length of fuse, 24 seconds. This battery (two 13-inch mortars) will continue firing at the rate of fifteen minutes to each mortar alternately, varying the charge of mortars and the length of fuse so that the shells will drop over the arches of the north and northeast faces of the work and explode immediately after striking, and not before.

The other batteries will open as follows, viz, Battery Stanton (three 13-inch mortars, 3,400 yards distant) immediately after the signal, at the rate of fifteen minutes for each piece, alternating from the right. Charge of mortars, 14 pounds; charge of shell, 7 pounds; elevation, 45 degrees; length of fuse, 23 seconds; varying the charge of mortar and length of fuse as may be required. The shells should drop over the arches of the south face of the work and explode immediately after striking, but not before.

Battery Grant (three 13-inch mortars, 3,200 yards distant) immediately after the ranges of Battery Stanton have been determined, at the rate of fifteen minutes for each piece, alternating from the right. Charge of shells, 7 pounds; elevation, 45 degrees; charges of mortars and length of fuse to be varied to suit the range, as determined from Battery Stanton. The shells should drop over the south face of the work and explode immediately after striking, but not before.

Battery Lyon (three 10-inch columbiads, 3,100 yards distant), with a curved fire, immediately after the signal, allowing ten minutes between the discharges for each piece, alternating from theright. Charge of gun, 17 pounds; charge of shell, 3 pounds; elevation, 20 degrees, and length of fuse, 20 seconds; charge and length of fuse to vary as required. The shells should pass over the parapet into the work, taking the gorge ms north face in reverse, and exploding at the moment of striking or immediately after.

Battery Lincoln (three 8-inch columbiads, 3,045 yards distant), with a curved fire, immediately after the digna allowing six minutes between discharges for each piece, alternating from the right. Charge of gun, 10 pounds; charge of shell, 13 pounds; elevation, 20 degrees, and length of fuse, 20 seconds. Directed the same as Battery Lyon ope the gorge and north face in reverse, varying the charge and length of fuse accordingly.

Battery Burnside (one 13-inch mortar, 2,750 yards distant) firing every ten minutes » from the time the range is obtained for Battery Sherman. Charge of shell, 7 pounds; elevation, 45 degrees ; charge of mortar and length of fuse varying as required from those obtained for Battery Sherman. The shells should drop on the arches of the north and northeast faces, and explode immediately after striking, but not before.

Battery Sherman (three 13-inch mortars, 2,650 yards distant) commencing immediately after the ranges for Battery Grant have been determined, and firing at the rate of fifteen minutes for each piece, alternating from the right. Charge of shell, 7 pounds elevation, 45 depress: charge of mortar and length of fuse to be fixed to suit the range, as determined from Buttery Grant. The shells should drop over the arches of the north and northeast faces.

Battery Scott (three 10-inch and one 8-inch columbiads, 1,740 yards distant) firing solid shot, and commencing immediately after the barbette fire of the work has ceased. Charge of 10-inch columbiads, 20 pounds; elevation, 44 degrees. Charge of 8-inch columbiad, 10 pounds; elevation, 5 degrees. This battery should breach the pancoupé between the south and southeast faces, and the embrasure next to it, in the southeast face, the elevation to be varied accordingly; the charge to remain the same. Until the elevation is accurately determined each gun should fire once in ten minutes; after that every six or eight minutes.

Battery Sigel (five 30-pounder Parrotts and one 48-pounder James, old 24-pounder rifled, 1,670 yards distant) to open with 43-seconds fuses on the barbette guns of the fort at the second discharge from Battery Sherman. Charge for 30-pounder, 3} pounds; charge for 45-pounder, 5 pounds; elevation, 4 degrees for both calibers. As soon as the barbette fire of the work has been silenced this battery will be directed with percussion shells upon the walls, to breach the pan-coupé between the south and southeast faces, the elevation to be varied accordingly, the charge to remain the same. Until the elevation is accurately determined each gun should fire once in six or eight minutes; after that every four or five minutes.

Battery McClellan (two 84 and two 64-pounders James, old 42 and 32 pounders rifled, 1,650 yards distant) opens fire immediately after Battery Scott. Charge for 84-pounder, 8 pounds; charge for 64-pounder, 6 pounds; elevation for 84-pounder, 4} degrees, an for the 64-pounder, 4 degrees. Each piece should fire once every five or six minutes after the elevation has been established. Charge to remain the same. This battery should breach the work in the pan-coupé between the south and southeast faces and the embrasure next to it in the southeast face. The steel scraper for the grooves should be used after every fifth or sixth discharge.

Battery Totten (four 10-inch siege mortars, 1,650 yards distant) opens fire immediately after Battery Sigel, firing each piece about once in five minutes. Charge of mortar, 34 fuse, 184 seconds. The charge of mortar and length of fuse to vary so as to explode the shells over the northeast and southeast faces of the work. If any battery should be unmasked outside the work, Battery Totten will direct its fire upon it, TeDe the charge and length of fuse accordingly. The fire from each battery will cease at dark, axcept especial directions be given to the contrary. A signal officer at Battery Scott, to observe the effect of the 13-inch shells, will be in communication with other signal officers stationed near Batteries Stanton, Grant, and Sherman, in order to determine the range for these batteries in succession.

By order of Brig. Gen. Q. A. Gillmore: