at that post. Mr.
O'Brien said he cared a good deal more about the loss of his operators
than he did for the loss of the cattle and rations, for it was very hard
to get competent operators at that time. There was at least one vacancy
at Washington following this incident.

Still another arm of the service was the pontoniers, whose duty it was
to bridge non-fordable rivers. They were armed and drilled as infantry,
but only for their own protection. Their specialty was laying and
removing pontoon bridges. A pontoon train consisted of forty to fifty
wagons, each carrying pontoon boats, with plank and stringers for
flooring and oars and anchors for placing. In laying a bridge these
boats were anchored side by side across the stream, stringers made fast
across them, and plank then placed on the stringers. Every piece was
securely keyed into place so that the bridge was wide enough and strong
enough for a battery of artillery and a column of infantry to go over at
the same time. The rapidity with which they would either lay or take up
a bridge was amazing. If undisturbed they would bridge a stream two
hundred yards wide in thirty minutes. They bridged the Rappahannock at
Fredericksburg under fire on the 12th of December, 1863, in a little
over an hour, losing heavily in the act.

Having now given some account of the organization of this great
human fighting machine, it will be proper to show how it was
handled. For this purpose there were four staff departments,
namely, the adjutant-general's, the quartermaster-general's, the
commissary-general's, and the ordnance departments. The first named was
the mouth-piece of the army. All orders were issued by and through that
officer. It was the book-keeper of the army. Each subdivision of the
army had its adjutant-general down to the office of adjutant in the
regiment, who was charged with issuing all orders, and with attending to
their execution. He was secretary, so to speak, of the commanding
officer, and his chief executive officer as well. Extraordinary
executive talent and tireless energy were required in these positions.
The adjutant must be able at all times to inform his chief of the
condition of every detail of the command whether an army corps or
regiment, exactly how many men were fit for duty, how many sick or
disabled, and just where they all are. In fact, he must be a walking
encyclopaedia of the whole command; added to this he was usually chief of
staff, and must b