The process of infiltration from a military standpoint means exactly the same thing as the word means in any other connection. A few men at a time filter into protected positions close to the enemy until enough have assembled to offer battle, the enemy meanwhile being kept down by strong, concentrated fire from the main body and the artillery. Although much slower than an assault, this is extremely economical of men.
During this progress from the Marne northward, the various headquarters had found some difficulty in keeping in touch with the advancing columns. A headquarters, even of a regiment, is not so mobile as the regiment itself. There is a vast amount of paraphernalia and supplies to be moved, yet it is necessary that a reasonably close touch be maintained with the fighting front.
The German method of retreat necessarily resulted in the Americans' going forward by leaps and bounds. Strong points, such as well-organized villages, manned by snipers and machine guns in some force, held the troops up until the German rear-guards were disposed of. Once they were cleaned up, however, the American advance, hampered only by hidden sharpshooters and machine guns in small strength, moved forward rapidly. It was reported, for instance, that one regimental headquarters was moved three times in one day to keep up with the lines.
Most of the time, regimental, and even brigade, headquarters were under artillery fire from the German big guns, and it was from this cause that the first Pennsylvania officer of the rank of lieutenant-colonel was killed, July 28th. He was Wallace W. Fetzer, of Milton, Pa., second in command of the 110th.
Regimental headquarters had been moved far forward and established in a brick house in a good state of preservation. The office machinery just was getting well into the swing again when a high explosive shell fell in the front yard and threw a geyser of earth over Colonel Kemp, who was at the door, and Lieutenant-Colonel Fetzer, who was sitting on the steps.
A moment later a second shell struck the building and killed three orderlies. This was good enough evidence for Colonel Kemp that his headquarters had been spotted by Boche airmen, for the artillery was registering too accurately to be done by chance, so he ordered a move.
Officers and men of the staff were packing up to move and Lieutenant Stewart M. Alexander, Altoona, Pa., the regimental intelligence officer, was finishing questioning two captured Hun captains when a big high-explosive shell scored a direct hit on the building. Seventeen men in the house, including the two German captains, were killed outright. Colonel Kemp and Lieutenant-Colonel Fetzer had left the building and were standing side by side in the yard. A piece of shell casing struck Colonel Fetzer, killing him, and a small piece struck Colonel Kemp a blow on the jaw, which left him speechless and suffering from shell-shock for some time.
Lieutenant Alexander, face to face with the two German officer prisoners, was blown clear out of the building into the middle of the roadway, but was uninjured, except for shock.
It was this almost uncanny facility of artillery fire for taking one man and leaving another of two close together, that led to the fancy on the part of soldiers that it was useless to try to evade the big shells, because if "your number" was on one it would get you, no matter what you did, and if your number was not on it, it would pass harmlessly by. Thousands of the men became absolute fatalists in this regard.
Major Edward Martin, of Waynesburg, Pa., took temporary command of the regiment and won high commendation by his work in the next few days.