The work to be done, to make our position as strong against the enemy as his was against us, was very great.  The problem was also complicated by our wanting our line as near that of the enemy as possible.  We had but four engineer officers with us.  Captain Prime, of the Engineer Corps, was the chief, and the work at the beginning was mainly directed by him.  His health soon gave out, when he was succeeded by Captain Comstock, also of the Engineer Corps.  To provide assistants on such a long line I directed that all officers who had graduated at West Point, where they had necessarily to study military engineering, should in addition to their other duties assist in the work.

The chief quartermaster and the chief commissary were graduates.  The chief commissary, now the Commissary-General of the Army, begged off, however, saying that there was nothing in engineering that he was good for unless he would do for a sap-roller.  As soldiers require rations while working in the ditches as well as when marching and fighting, and as we would be sure to lose him if he was used as a sap-roller, I let him off.  The general is a large man; weighs two hundred and twenty pounds, and is not tall.

We had no siege guns except six thirty-two pounders, and there were none at the West to draw from.  Admiral Porter, however, supplied us with a battery of navy-guns of large calibre, and with these, and the field artillery used in the campaign, the siege began.  The first thing to do was to get the artillery in batteries where they would occupy commanding positions; then establish the camps, under cover from the fire of the enemy but as near up as possible; and then construct rifle-pits and covered ways, to connect the entire command by the shortest route.  The enemy did not harass us much while we were constructing our batteries.  Probably their artillery ammunition was short; and their infantry was kept down by our sharpshooters, who were always on the alert and ready to fire at a head whenever it showed itself above the rebel works.

In no place were our lines more than six hundred yards from the enemy.  It was necessary, therefore, to cover our men by something more than the ordinary parapet.  To give additional protection sand bags, bullet-proof, were placed along the tops of the parapets far enough apart to make loop-holes for musketry.  On top of these, logs were put.  By these means the men were enabled to walk about erect when off duty, without fear of annoyance from sharpshooters.  The enemy used in their defence explosive musket-balls, no doubt thinking that, bursting over our men in the trenches, they would do some execution; but I do not remember a single case where a man was injured by a piece of one of these shells.  When they were hit and the ball exploded, the wound was terrible.  In these cases a solid ball would have hit as well.  Their use is barbarous, because they produce increased suffering without any corresponding advantage to those using them.