nstalled, little change is
possible during an attack, so that the operation of fighting a system of
defence, such as we have considered above, is mainly a matter of peace
training of gun-crews, electric light men and look-outs, coupled with
careful organization. To facilitate the transmission of order and
intelligence, a considerable system of telephonic and other electrical
communication has been established. This may be considered under the
three heads of (1) orders, (2) intelligence, (3) administration.

The communication of _orders_ follows the organization adopted for the
whole fortress. Each fortress is commanded by a fortress commander, who
has a suitable staff. This officer sends orders to commanders of
artillery, engineers, and infantry. The artillery officer in charge of a
group of batteries is called a "fire commander"; his command is
generally confined to such batteries as fire over the same area of water
and can mutually support one another. Thus there may be several fire
commanders at a defended port. Anti-torpedo boat batteries are not in a
fire command, and are connected to the telephone system for intelligence
only and not for orders. The engineers require orders for the control of
electric lights or Brennan torpedo. The officer in charge of a group of
lights or of a torpedo station is called a director. Though receiving
orders direct from the fortress commander, he has also to co-operate
with the nearest artillery commander. The infantry are posted on the
flanks of the fixed defences, or on the land front. They are divided
into suitable groups, each under a commanding officer, who communicates
with the fortress commander. In large fortresses the area is divided
into sections, each including some portion of the artillery, engineers,
and infantry defence. In such cases the section commanders receive
orders from the fortress commander and pass them on to their
subordinates.

The _intelligence_ system includes communication with the naval signal
stations in the vicinity, one of which is specially selected for each
port as the warning station and is directly connected to some part of
the defences. Another part of the intelligence system deals with the
arrangements for examining all ships entering a harbour. This is usually
effected by posting in each entrance examination vessels, which are in
communication by signal with a battery or selected post on shore. Any
points on shore which can see the approaches