September-October - Air Defense Artillery

AAA Planning for Waterborne
r Invasion
By Colonel M. R. Thompson, Coast Artillery Corps
The third time I was fortunate enough to get in on a
full-scale waterborne invasion I determined to keep notes
on all the steps taken in the AA planning, hoping such
notes might serve as a guide for someone else. But as the
planning, which started about 6 January, did not culminate
ina D Day until 15 August, the chronological record is more
confusing than instructive and I have reorganized the material
into what I hope is a more intelligible sequence.
Early in the war there seemed to be a tendency in the
U. S. to accept as gospel the words written baCk or brought
back by officers overseas, without the realization that any
one officer's conclusions are colored, indeed created by his
particular and limited experiences. These experiences are
certain to include items of climate, terrain, tactics, and even
materiel peculiar to the theater he was in or the enemy he
I fought. That I recognize this does not mean that I am
immune to the same influences. All that follows, therefore,
bears the stamp of such special circumstances as obtained
in the invasions of Sicily and 'Southern France, in the
planning of which I had a hand, as well as the invasion
of French Morocco, where I was in on the execution only.
One more word of caution: \Vatch out for rules. The use
of specific rules as a guide is excellent. Any attempts to
substitute them blindly for judgment may be fatal. I have
{ some confidence in my judgment in the AAA planning of
an amphibious operation.
109 my own.
I take a dim view of rules, includ-
PRELIMINARIES
The planning of a full-scale waterborne,invasion of hostile
shores is alwavs listed as one of the most difficult tasks
that can confront; Staff. Repetition improves the performance
but multiplies the details, because more is learned at
each repetition. For a major operation involving two or more
corps, considerable time must be available. Once the planning
commences, time will pass with increasing rapidity,
and the things that must be done pile higher and higher.
From the date th~ major forces for the invasion are determined,
not less than 90 days should elapse before the Force
sails for its destination. During that period the assault elements
must receive amphibious training and special training
based on the climate, terrain and defenses to be encountered;
they must be checked as to equipment and personnel,
must be moved to embarkation points and mounted.
All follow-ups must be trained and equipped where necessary,
and phased to move to points of embarkation. Simultaneously,
all plans for the operation must be perfected,
alternate plans devised, Naval and Air action coordinated,
and an increasingly large number of officers made cognizant
of portions or all of the details. Security of the plans necessitates
this number being kept to the minimum at all stages;
the necessity for information and planning requires that I
m~r_eand more individuals be brought into the picture. I
Ihe first step in an amphibious operation as in any operation
is the determination and assignment of a mission by I
higher authority. On the Army level, the mission will be
in general terms, somewhat as follows: "Effect a landing in
the general area 'A,' establish a beachhead and secure a
finn base for future operations." I
Frequently the nature of the future operations will be
indicated, but this will not always be the case, since those I
operations may depend, not only on the success of the beachhead
but also on unpredictable circumstances obtaining else- I
where at the time.
In general the vVar Department or the Theater Com- I
mander will indicate the approximate size (in Divisions)
of the forces to be available or a decision on this matter will
be made after preliminary studies.
At this point or earlier, the Force Commander should
assemble a complete staff, including planning sections of
the Navy and Air Force, in an appropriate area, preferably
under one roof or in adjacent buildings, under appropriate
conditions of secrecy. The process of planning consists
thenceforth of a series of trial and error planning, by each
section, based on the information currently available.
ORGANIZATION OF THE ANTIAIRCRAFT ARTILLERY
The organization of AAA with an Arn1Y' Corps or Division
has not been fully determined. For a Task Force the
question must be determined by the organization of the
Task Force, the mission, the probable amount of AM involved
in each echelon, and such considerations of experience
of units, width of the assault area, and subsequent
operations as will affect the subject.
The set-up should satisfy the following requirements:
a. Flexibility. Since, in the initial phases, action will be
under sub-Task Force Commanders, usually Divisions, responsibility
for AA Defense must be vested in the sub-Ta~k
Force Commanders, and they must be given adequate AAA
Headquarters for control. Subsequently, with the arrival of
Corps Headquarters and the joining of the separate assaults,
Corps will take over control of at least the AA defense in
rear of division boundaries, and of airfields, and Corps Artillery
positions within Division areas. Corps may take control
of all AAA, placing certain units in direct support of
each Division. Later, with the arrival of Army Headquarters,
the latter will take over all AA defense of vulnerable
points in rear of Corps boundaries and of certain points as
Airfields and Army installations within Corps areas. Finally,
with the advance of the forces from the shoreline, the defense
of areas in rear of the Armv and of some, as airfields,
within Army boundaries will be'taken over by an Air De-