regiments of volunteer infantry detailed on the 19th ultimo as the guard of the advanced trenches, were to-day relieved from this responsible and hazardous duty. Their aggregate number of casualties in this brief period is 105, or 10 per cent. of the whole force.* Four fifths were caused by the enemy's artillery fire. Captain Randlett was conspicuously efficient. The engineers will long remember these regiments as their special guard during the most critical part of the siege; also for their assistance in the sap, at which work a detail was constantly employed.

Friday, September 4.-Captain Walker reports:

During my tour of duty this morning, the sap was run 25 feet, when the enemy opened upon us a very heavy fire of artillery, compelling us to stop the advance and strengthen that which had already been built. The parapet proved able to withstand the fire, but it was pretty well knocked out of shape.

Emplacements were prepared on the right of the third parallel for two 10-inch siege mortars, which were soon afterward mounted there. Magazine material for 10-inch mortars was brought to the fifth parallel. Other work in progress as yesterday.

The parapet of the bayou built immediately in rear of the fifth parallel formed parades for the parallel itself, thus protecting it from our own shells. A boat expedition was sent against Battery Gregg, which was unsuccessful.

Saturday, September 5.-This morning the long-expected, and, by the sappers, anxiously hoped for, bombardment of Wagner by all the land batteries and the Ironsides began, and with it ended all the difficulties in sapping against the work, for the enemy's fire, sharpshooters and all, is completely subdued, and his distant batteries dare not fire at our advance for fear of injuring their friends in the fort.

In the past two and one-half days, at considerable sacrifice, not more than 25 yards of sa+ have been executed, and it, from its direction, brought us no nearer the fort. To-day more than 150 yards, most of it by the flying sap,+ have been built without loss of life. The head of the sap is now opposite the ditch of Wagner; from it fragments of shell can be easily thrown by hand into the work.

The trace of the approach executed to-day is a succession of short zigzags made necessary by the narrow front. Captain Walker was in charge of this work.

Magazine for the 10-inch mortars, in the fifth parallel, is completed and in use. Fascines were carried forward for use in the seaward parapet in advance of the fifth parallel.

During the past two days, by order of the general commanding, I have examined several prisoners, and have from them obtained additional information, which enabled me to draw a plan of Wagner, which was afterward found to contain no material error. At the request of General Terry, 20 copies were furnished for the officers who were to go in the assaulting column of the 7th instant.

Sunday, September 6.-I reported for duty last night, and was assigned this morning to my original work, by order of the general commanding.

The sap is progressing to-day. One branch is to pass to the left and the other to the right of the bastion of the fort, thus enveloping it.

To-day, as yesterday, men are constantly exposing themselves above the parapets without drawing any fire from the enemy. Indeed, in the extreme front, there is no danger excepting from our own

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*See Note 18, p. 326.

+See Note 13, p. 323.

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