Reference Winch 6, paragraph 4. [1]

I have obtained the views of our Chiefs of Staff on the danger of
invasion and the reinforcement of our home defence forces. They
are as follows:-

THE DANGER OF INVASION OF AUSTRALIA IN FORCE
1. So long as we retain a foothold in Malaya and the Islands of
the Malay Barrier remain in our hands we do not consider that
Japan will attempt a major attack against Australia. Her method is
likely to be the step by step policy which has so far had
conspicuous success. But, with the land, sea and air forces at her
disposal and the merchant shipping she has available, the direct
move towards Australia from bases in the mandated islands grows
more probable. This is also likely to take the form of a
progressive southward move securing New Guinea, New Hebrides and
New Caledonia as advanced bases from which to sever our sea
communications and from which a major attack could be launched on
Australia if and when the strategic situation in the area of
Malaya and Netherlands East Indies is judged to be suitable.

2. In this connection, the United States [of] America [Pacific]
fleet has to be considered. Although it has obviously suffered
severe material and moral damage, we do not consider that, until a
decisive fleet action has resulted in favour of Japan, the latter
would attempt a sea movement, from advanced bases in the Islands
to the north and north-east, of the size necessary for a major
attack on the mainland of Australia.

3. Our immunity from invasion accordingly depends on our ability
to maintain our position in Malaya and the Netherlands East Indies
and on the threat of the United States [of] America [Pacific]
fleet against the long Japanese sea lines of communication to the
South. These are imponderable factors, but, in view of what has
happened since the outbreak of war with Japan, it would be folly
for us to suggest that these factors will operate in our favour.

It is a race against time in Malaya in which the enemy will do
everything possible by air and submarine attacks to prevent our
reinforcements getting through. Should we lose Singapore, our
prospects of retaining Sumatra would be poor. Lastly, control of
the Pacific can be won or lost in one fleet action.

4. We therefore consider that the danger of invasion in force will
remain until we have clearly stabilised our front along the Malay
barrier or until we have secured supremacy over the Japanese
fleet.

THE REINFORCEMENT OF THE HOME DEFENCE FORCE
5. The great extent of our vulnerable coastline renders inevitable
a very large degree of dispersion of our land and air forces. The
reserves available are therefore limited in number and are further
limited in scope owing to the distances over which they may have
to be moved to meet any serious threat.

6. Should Japan secure complete freedom of the seas, the only
limit to the forces she could employ against us would be that
imposed by the amount of shipping available to her.

7. It is clearly beyond our capacity to meet an attack of the
weight that the Japanese could launch. At the same time, our
limitations in both manpower and equipment deny us the capacity to
increase our land forces to an appreciable extent. Any
reinforcement, provided it is adequately trained and equipped,
must increase our security by providing a greater deterrent to
attack.

8. We assume that if the proposal is implemented American troops
would be subject to the Chief of the General Staff in respect of
training and operations.

9. Apart from the question of Australian security, Australia is an
admirable base for reinforcements for offensive action against the
Japanese in the South-West Pacific area, and it is desirable that
forces available for this purpose should be located here as soon
as possible.

The War Cabinet and the Advisory War Council welcome the
suggestion that our land forces should be reinforced by American
formations. [2] We assume that their full equipment would be
provided by the United States [of] America Government. We should
like to make it clear that the provision of United States troops
alone in the strength which you indicate is not of course the sole
measurement of our needs. We have, as you are aware, serious
deficiencies in aircraft and other equipment about which we have
already made representations through our representatives in London
and the United States [of] America.

CURTIN