On the 16th the general movement was continued, when Lost Mountain was abandoned by the enemy.  Our right naturally swung round, so as to threaten the railroad below Marietta, but Johnston had still further contracted and strengthened his lines, covering Marietta and all the roads below.

On the 17th and 18th the rain again fell in torrents, making army movements impossible, but we devoted the time to strengthening our positions, more especially the left and centre, with a view gradually to draw from the left to add to the right; and we had to hold our lines on the left extremely strong, to guard against a sally from Kenesaw against our depot at Big Shanty.  Garrard’s division of cavalry was kept busy on our left, McPherson had gradually extended to his right, enabling Thomas to do the same still farther; but the enemy’s position was so very strong, and everywhere it was covered by intrenchments, that we found it as dangerous to assault as a permanent fort.  We in like manner covered our lines of battle by similar works, and even our skirmishers learned to cover their bodies by the simplest and best forms of defensive works, such as rails or logs, piled in the form of a simple lunette, covered on the outside with earth thrown up at night.

The enemy and ourselves used the same form of rifle-trench, varied according to the nature of the ground, viz.:  the trees and bushes were cut away for a hundred yards or more in front, serving as an abatis or entanglement; the parapets varied from four to six feet high, the dirt taken from a ditch outside and from a covered way inside, and this parapet was surmounted by a “head-log,” composed of the trunk of a tree from twelve to twenty inches at the butt, lying along the interior crest of the parapet and resting in notches cut in other trunks which extended back, forming an inclined plane, in case the head-log should be knocked inward by a cannon-shot.  The men of both armies became extremely skillful in the construction of these works, because each man realized their value and importance to himself, so that it required no orders for their construction.  As soon as a regiment or brigade gained a position within easy distance for a sally, it would set to work with a will, and would construct such a parapet in a single night; but I endeavored to spare the soldiers this hard labor by authorizing each division commander to organize out of the freedmen who escaped to us a pioneer corps of two hundred men, who were fed out of the regular army supplies, and I promised them ten dollars a month, under an existing act of Congress.  These pioneer detachments became very useful to us during the rest of the war, for they could work at night while our men slept; they in turn were not expected to fight, and could therefore sleep by day.  Our enemies used their slaves for a similar purpose, but usually kept them out of the range of fire by employing them to fortify and strengthen the position to their rear next to be occupied in their general retrograde.  During this campaign hundreds if not thousands of miles of similar intrenchments were built by both armies, and, as a rule, whichever party attacked got the worst of it.