That's a coincidence, just this afternoon I was reading ' Three Years in the Sixth Corps ' by George T Stevens, a Kindle book. He describes how during an advance on abandoned Confederate works during the Peninsular campaign, " As the 77th regiment passed along one of the roads leading among the entrenchments, a sharp report like that of a pistol was heard at the feet of those in the center of the column and directly under the Colors. The men scattered and a piece of old cloth was seen lying on the ground at the point from which the report emanated. Colonel McKean who was very near lifted the cloth with the point of his sword and discovered a torpedo carefully buried in the ground. " He goes on to say how they had been lucky in that on this occasion only the fuse had exploded but other regiments had not been so lucky as there were many more torpedos buried in the area, their fuses covered with a piece of rag or bark and how many men had been killed or wounded.