“The engineers were under imperative orders”

His official report on the Battle of Little Round Top, as published in the U.S. Congressional Record
Context: The enemy seemed to have gathered all their energies for their final assault. We had gotten our thin line into as good a shape as possible, when a strong force emerged from the scrub wood in the valley, as well as I could judge, in two lines in echelon by the right, and, opening a heavy fire, the first line came on as if they meant to sweep everything before them. We opened on them as well as we could with our scanty ammunition snatched from the field.
It did not seem possible to withstand another shock like this now coming on. Our loss had been severe. One-half of my left wing had fallen, and a third of my regiment lay just behind us, dead or badly wounded. At this moment my anxietv was increased by a great roar of musketry in my rear, on the farther or northerly slope of Little Round Top, apparently on the flank of the regular brigade, which was in support of Hazlett's battery on the crest behind us. The bullets from this attack struck into my left rear, and I feared that the enemy might have nearly surrounded the Little Round Top, and only a desperate chance was left for us. My ammunition was soon exhausted. My men were firing their last shot and getting ready to "club" their muskets.
It was imperative to strike before we were struck by this overwhelming force in a hand-to-hand fight, which we could not probably have withstood or survived. At that crisis, I ordered the bayonet. The word was enough. It ran like fire along the line, from man to man; and rose into a shout, with which they sprang forward upon the enemy, now not 30 yards away. The effect was surprising; many of the enemy's first line threw down their arms and surrendered. An officer fired his pistol at my head with one hand, while he handed me his sword with the other. Holding fast by our right, and swinging forward our left, we made an extended " right wheel," before which the enemy's second line broke and fell back, fighting from tree to tree, many being captured, until we had swept the valley and cleared the front of nearly our entire brigade.