While the US wasn’t in the war, many people in the US military knew that it was only a matter of time before we got sucked in.
Over a year before the attack on Pearl Harbor, a plan was developed for just that eventuality.
Learn more about the Plan Dog Memorandum on this episode of Everything Everywhere Daily.
Prior to the second world war, one of the major principles of the United States which was seldom violated, and never seriously questioned, was the principle of neutrality.
It actually dated back to George Washington’s farewell address when he warned the country to steer clear of making alliances with European powers.
The European continent had, for centuries, been one of almost non-stop warfare.
Washington knew that no matter who we allied with, it would wind up with the US getting caught in a European war.
So for 150 years, that was the underlying foreign policy of the United States. We fought a war with Spain, which was a European power, but it wasn’t a war in Europe per se.
The principle was violated for the first time in the first world war, but soon after the war ended, the US treated it as a temporary aberration and went back to their policy of neutrality.
Thought the 1930s, as Japan conquered Manchuria and Germany absorbed Austria and the Sudentenland the US didn’t get involved.
However, even if politically the United States was staying out of the conflict, planners in the US military weren’t doing nothing.
Right after the first world war ended, the US Navy began developing plans for a possible war with Japan. The plan, first adopted in 1924, was known as Joint Basic War Plan – Orange.
This plan was updated many times over the years as circumstances and technology changed, but it served as a basic blueprint for what would happen in the event of a war.
The general assumptions of the plan were that it would involve some sort of Japanese blockade of the Philippines and other US islands in the Pacific. Local forces would try to hold out while the Pacific fleet got organized in California and Hawaii, and the Atlantic fleet would arrive later, coming through the Panama Canal.
The war would be fought like all other wars with some grand battle of surface ships, most probably battleships.
While Orange was the best-known plan, there were other plans as well including a Black plan for dealing with Germany, and various shades of Red for going to war with the British.
The problem with all these plans is that events constantly change which requires constant updating of the plans.
In the 1930s, it wasn’t just the political situation that was changing rapidly, it was also the technology. Many of the assumptions of naval warfare were thrown out the window with the rapid improvements in aircraft and aircraft carriers.
When war broke out in Europe, planners began to realize that the one-on-one wars that they had been planning might not be the most probable scenario. They began seriously considering the possibility of a two-front war, one in Asia and one in Europe.
So, in 1939, all of the color plans were thrown out, and five new plans were developed to cover the contingencies that were developing at that moment. They were known as the Rainbow plans.
Rainbow Plan 1 was basically a plan to fight a defensive war in the Western Hemisphere as far as 10 degrees latitude south. This plan assumed no allies.
Rainbow Plan 2 was the same scenario as Rainbow Plan 1, but with allies such as France and Britain.
Rainbow Plan 3 was a modification of the original Orange Plan, but securing Rainbow Plan 1 first, and then engaging the Japanese in the Pacific.
Rainbow Plan 4 was an extension of Rainbow Plan 1 but covered the entire Western Hemisphere.
Rainbow Plan 5 assumed the protection of Rainbow Plan 1 but then working with the French and British in North Africa and Europe.
The Rainbow Plans were approved in March 1939.
However, there was a whole lot that happened after March of 1939. As war broke out, possible outcomes became much clearer. In May 1940, France was taken off the table as a possible ally when they were overrun by Germany.
It was in this light that a modification of the Rainbow Plans was drawn up in a memorandum written by Chief of US Naval Operations, Admiral Harold Stark.
In it, Stark outlined four possible scenarios in which the United States might join the war which was now raging in both Europe and Asia.
Scenario A: War with Japan where the United States has no allies.
Scenario B: War with Japan where the United States would be allied with either the British or the Dutch East Indies.
Scenario C: War with Japan where Japan is aided by Germany and Italy, and the US may or may not have allies.
Scenarios D: War with Germany and Italy where Japan isn’t involved right away, and the US is allied with the British.
Finally, there was Scenario E: This was the isolationist option where the US would just defend the western hemisphere, and continue to supply Britain.
The recommendation which was given in the memorandum was option D, which was war with Germany and Italy. Admiral Stark stated in the memorandum:
I believe that the continued existence of the British Empire, combined with building up a strong protection in our home areas, will do most to ensure the status quo in the Western Hemisphere, and to promote our principal national interests. As I have previously stated, I also believe that Great Britain requires from us very great help in the Atlantic, and possibly even on the continents of Europe or Africa, if she is to be enabled to survive. In my opinion Alternatives (A), (B), and (C) will most probably not provide the necessary degree of assistance, and, therefore, if we undertake war, that Alternative (D) is likely to be the most fruitful for the United States, particularly if we enter the war at an early date
Because of the Army/Navy phonetic alphabet at that time, the word for D was Dog, and because Plan D or Plan Dog was advocated, this became known as the Dog Plan Memorandum.
In common parlance, this became known as the Europe First strategy, which is basically what the actual grand strategy was when the war arrived. It was never formally adopted, but it informally had the support of the top military leaders and President Roosevelt.
I’ll be honest, I’ve often wondered why America adopted a Europe First strategy when it was Japan that got them into the war.
The more research I’ve done, the more the strategy makes sense.
First, in 1940, the Soviet Union still wasn’t in the war. They were not quite allies with Germany, but not quite enemies either. It wasn’t until Germany turned on the Soviets that they became allies of necessity, but that couldn’t be planned for in 1940.
The second was just the political reality of dealing with Churchill. The UK was on the ropes and really really wanted the US to join the war effort. After Pearl Harbor, Churchill flew to Washington just two weeks later to ensure the Americans were on board with the Europe First strategy.
Last, and most importantly, it just made strategic sense. If the British had gone down in defeat, then everything would have become much much more difficult.
If the US focused on Japan first, there was a very real risk at the time that the UK might not be around to be an ally once the US turned its attention to Europe.
However, if the US could protect the UK and partner with them to win the war in Europe, then they would have the British military to help them win the war against Japan later on.
The assumption in 1941 was still that it wouldn’t be possible to simultaneously fight a two-front war, with both fronts at full strength.
As it turned out, that is pretty much what happened. A two-front war was fought at full strength, and both theaters ended within a few months of each other.
When Pearl Harbor was attacked in December 1941, the US was taken by surprise, but they weren’t totally caught off guard. While they didn’t know how they would enter the war, they were certainly prepared for the eventuality.
Once they were in the war, they were able to have a head start thanks to strategies outlined in the Plan Dog Memorandum.