War Plan Orange (commonly
known as Plan Orange or just
Orange) refers to a series of United States Joint Army and
Navy Board war plans for dealing with a possible war with
Japan during the interwar
The plans were begun informally in 1919 and
formally adopted by the Joint Army and Navy Board beginning in
1924. Predating the Rainbow plans
which presumed the assistance of allies
Orange was predicated on the U.S. fighting Japan alone.
anticipated a withholding of supplies from the Philippines and other U.S. outposts in the Western Pacific
(they were expected to hold out on their own), while the Pacific Fleet marshaled its
strength at bases in California, and guarded against attacks on the Panama Canal. After mobilization (the ships maintained only
half of their crews in peacetime), the fleet would sail to the
Western Pacific to relieve American forces in Guam and the
Philippines. Afterwards, the fleet would sail due north
for a decisive battle against the Imperial Japanese Navy, and then
blockade the Japanese home
The Imperial Japanese Navy developed a counter-plan to allow the
Pacific Fleet to sail across the Pacific while using submarines and
carrier attacks to weaken it. The Japanese fleet would then attempt
to force a battle against the U.S. in a "decisive battle area",
near Japan, after inflicting such attrition. This is in keeping
with the theory of Alfred Thayer
, a doctrine to which every major navy subscribed before
World War II
, in which wars would be
decided by engagements between opposing surface fleets (as they had
been for over 300 years). It was the basis for Japan's demand for a
70% ratio (10:10:7) at the Washington Naval Conference
which would give Japan superiority in the "decisive battle area",
and the U.S.'s insistence on a 60% ratio, as 70% superiority was
believed to be necessary for a successful attack.
The American war planners failed to appreciate that technological
advances in submarines
and naval aviation
had made Mahan's doctrine
obsolete. In particular, the American planners did not
understand that aircraft could sink battleships, nor that Japan
might put the U.S. battleship force (the Battle Line) out of action
at a stroke--as it did at Pearl Harbor.
American plans changed after this attack. Even after major
Japanese defeats like Midway, the U.S.
fleet favored a methodical "island-hopping" advance, never going far
beyond land-based air cover.
Moreover, by their obsession with "decisive battle", the Imperial
Japanese Navy would ignore the vital role of anti-submarine warfare
. Germany and the U.S.
would demonstrate the need for this with their submarine campaigns
against Allied and Japanese merchant shipping
The American campaign ultimately choked
Japan's industrial production. Japan also notably failed to
institute an anti-commerce campaign themselves.
- Mahan, Alfred Thayer. The Influence of
Seapower on History, 1660–1783. Boston: Little, Brown,
copyright 1918, reprinted 1949.