Why did Adolf Hitler Declare War on the United States of America?
Some possible reasons why Hitler had
Lack of Documentation Leads to Speculation
One of the problems in researching Nazi WWII politics and the resulting policies that occurred in Germany during the 1930s thru to the end of the 2nd World War is that many of reasons behind the decisions were never documented. Some high ranking people in the Third Reich kept diaries, Josef Göbbels for example, but the writers often recorded what happened, the decisions that were made, but seldom the reasons behind the decisions that were made.
The style that Hitler used to govern the National Socialist Germans Workers Party (NSDAP, aka NAZI; the D stands for Deutschland), and thus Germany, was one of vaguely stating what he wanted done to various people or departments then those people would implement the policies and enforce it. He also often set up duplicate sets of government groups to carry out the same policies, building programs, enforcement, and had them competing against one another. This kept people fractured and thus he was kept him informed since most everything had to go through him to be approved. It also meant he often heard both sides of a position since two different groups were often given the same task. The charisma of that leader and their access to the Chancellor's office would dictate the power that the group had. Thus, if you were in favor with Hitler then you got prestige to speak on his behalf in your department as what rules to write and so your version of a policy implemented the way you wanted it, or a government contract. Meeting notes would be written down, but the reasoning behind Hitler's decision on that - policy papers, background materials, never were. Just decisions as to who was allowed to do what.
Treaties Before the Second World War
Military treaties took on a more serious note starting in the early 1800s. The military treaties were created for very specific reasons, intently enforced ,and advertised to other nations to an extent seldom seen since 1980. The active solicitation, enforcement, and advertisement of signed treaties is why smaller countries allied themselves with the larger ones: to help guarantee their protection from their neighbors. The smaller countries alliance was done to try and ensure that no neighboring country would dare attack them since it would bring in a very large country on their side which would then easily defeat the aggressor. However, the Balkan nations animosity toward each other stretched back hundreds of years and when these deep rooted fears, slights, religious differences, were brought to the forefront by the assassination, the worry of escalating into a larger conflict was not considered by these small countries: it was time to enforce the treaties signed over the previous decades.
Thus, when Austria-Hungarian Empire started military action the entangling treaties were honored by each nation which resulted in every nation but seven in Europe fighting in the Great War.
Inter-War Treaties and Nations and Violations
New nations also meant new military treaties. The most important treaties were the ones in central Europe with Poland, and the Czechoslovakian nation which was created out of Germany, Russia, and the Austro-Hungarian Empire.
Fear of War
The scope of the fighting in The Great War (only later referred to as World War One) was immense both in the losses of personnel, plus the monetary cost to pay for it, was a great inhibitor to the western nations. The politicians in charge in France and England (United Kingdom) especially, were very afraid of having another social and economic cost put onto their nations again. Politically they would lose their jobs. This was because many citizens were disillusioned with their leadership in the war, so the politicians in charge strove to avoid direct confrontation with Germany.
Adolf Hitler's Political Mind Set
Some of Hitler's ideas of what the west would do in a political situation were wishful thinking, some were confirmed based on the initial treaty violation gambles that the Hitler (legally Germany was still a Republic, but operationally it was a dictatorship) violated which were won. These initial political ploys, and the resulting successes, reinforced his initial mind set of the political will of the west so that in Herr Hitler's mental mind it became a fact as to what the west would always do in a future political or military crisis.
In 1927 Benito Mussolini became the legally elected head of the government in 1927, as did Hitler in 1933, and started to transform that nation into more of a constitutional dictatorship. His power was both granted by the government and limited at the same time. Elected government representatives had more influence in making policies than the German one did. (After the 1933 passage of the Enabling Acts by the German Reichstag, the Nazi party - Hitler - effectively became a dictatorship.) The basic idea of Fascism had been around a long time (just like Communism) but Italy was the first nation to elect it into a leadership roll thus controlling a nation.
The West's Mind Set
This did not fully prevent the French from creating new weapons, but these weapons were designed to support the defense of the Franco-German border.
A String of Political Victories Engineered by Hitler
A side effect of Hitler's success was that those within the German government who counciled against Hitler's gambles — which he continuously won — were deemed to be nay-sayers, weaklings, anti-German, anti NAZI Party, and were thus were marginalized and subsequently ignored (or never consulted again). Hitler's string of political victories would have never succeeded if more astute politicians had been in charge in the France and England. Adolf Hitler indeed understood his political opposites. The political and military planners within Germany itself whose advice was opposite of what Hitler planned to do, never took into any account the political aspect in their war planning.
The Danzig Corridor, created by the Treaty of Versailles, separated East Prussia from the rest of the German nation. This stretch of Poland was largely populated by ethnic Germans. As an artificial creation of other nations, neither Poland nor Germany liked the situation — but both had to deal with it. The fact that part of Poland now bisected Germany — done to ensure Poland had a path to the Baltic and to lessen Germany's ability to wage war by removing lots of territory that it controlled — angered Germans in general, and gave it an opportunity.
The Great War Lessons
The Imperial German submarine fleet was a great worry to the British. A single ship with 50 men could sink a battleship that has thousands on it. And they did. This arm of the German Navy was not as impressive to show off, nor were they a glory assignment to those in wanting to move up in rank, but the men in that unit were of the same high caliber - sometimes more - than the battleship fleet captains. Plus, they had to be naturally aggressive and independent thinkers to command a submarine. This natural tendency of ships of the line to downgrade other parts of the service to promote their own, it occurred in all navies, kept the U-Boat arm from accomplishing the task of taking Britain out of the war by stopping supplies to and from the British Isles.
A big factor in this failure was the politicians in Germany. The U-Boat was totally new weapon and no "rules" had been formulated to account for it — nor its best use and defense against it. Thus, it fell into a category of a "terror weapon." Using a submarine to its military advantage of stealth attack against all military targets and civilian shipping could bring more nations into the war against Germany. Civilians of a nation would be killed as a direct result of a conscious attack against them as they did their job.
This idea of not allowing submarines to attack - or attack in such a way as to almost ensure its destruction later on - was promoted heavily since England had the most to lose in a campaign of unrestricted submarine warfare.
There really had never been "civilian" ships during a war that was exempt from attack. Privateers had taken Spanish merchant ships during the many wars against Spain, US Civil War Confederate ships had sunk Northern ships and the Federals had in turn had captured or sunk Confederate flagged ships. The biggest difference between surface and U-Boat attacks was that the U-Boat attackers could not be detected till after the attack. These rules of engagement on the high seas against merchant ships dated back to the time of Henry the VII.
Initial WWI U-Boat Operations
This last change in combat restriction is what enabled the Lusitania to be attacked and sunk by a single torpedo (secondary explosion recorded by survivors of the ship and the German submarine captain was likely coal dust exploding in an empty coal bunker) in April of 1916 off the coast of Ireland. (3)
The drift toward un-announced attacks was caused by many factors one of which was the use of wireless on cargo ships. If a British merchant was stopped to be inspected, they had more than enough time to send a signal to announce the presence of a U-Boat before the enemy came on board to see if the ship was carrying war goods. During this time the Royal Navy would be on the way - and the U-Boat was certainly in danger then.
After the sinking of the Lusitania the un-conditional U-Boats attacks were suspended. Once again shipping proceed a lot easier to England on the high seas. In the spring of 1917 the German Navy convinced the German Government to again allow un-restricted U-Boat warfare and its reinstatement was just one of many factors that prodded the citizens of the US to push for war against the German Empire.
The German U-Boat fleet campaign from 1916 to 1917 when "sink on sight" was halted lost them the blockade war. During that suspension time the British Navy was heavy into developing anti-submarine equipment and tactics: both listening gear and the introduction of the convoy system. By the time in 1917 when un-restricted attacks resumed the tide had turned against the submarines and the successes that they had early in the war could not be repeated.
The United States entry into the war caused severe harm to the German naval effort: all the US flagged ships now could now be chartered by the US Government and be organized into a large scale supply system to send cargo to the war zone. The downside was that now a US flagged ship could be sunk.
A secondary effect of the US entering the war was that the need to use British yards to build more supply ships to replace those sunk instead of combat ships was not critical anymore. This allowed more warships to be built to fight the U-Boats - mainly destroyers.
The sudden influx of American cargo ships into the supply system, and the US ability to supply both raw and finished goods to the factories of the Allied Nations on a massive scale, ensured the defeat of the Kaiser's ground army in France and Belgium.
World War II
The Soviet Union (USSR) also did not protest - but of course the Soviet-Nazi treaty signed in August was the reason why. Late in September Soviet forces invaded Poland from the east and occupied the rest of the nation as negotiated in the treaty. Later on the Stalin's Soviet annexed Latvia, Lithuania, and Estonia into the Soviet Union. German units actually had to pull out of the land it had captured anywhere from 20 to 100 miles due to treaty. (4)
U-Boats On The Prowl
The same strategy of a U-Boat blockade that was pursued in World War I was again instituted. The Type VII U-Boat, however, was much better than the World War I counterpart. The tactics had also changed: they were centrally controlled and coordinated by Admiral Dönitz using Enigma encoded messages. (5)
The British Navy again instituted the convoy system after a few months and ships sailing from the world ports, when there was time enough to coordinate a convoy - and enough escorts were around - shipped sailed the blue oceans for protection from the U-Boat arm of the Kriegsmarine.
Problems With Neutral Countries
Even with these brazen acts, from war's start in 1939 thru December 1941, American ships could still sail the world's oceans to the allied nations without being attacked by German U-Boats.
When the war broke out the US population as a whole did not favor getting involved. The USA had gotten into the Great War in 1917, and the political aims of that war was never fullfilled — witness the failed League of Nations and now state of war in Europe. The population of the US was VERY much East coast and Midwest centered. A significant part of the population was only one or two generations removed from when their forbears had emigrated to the US. The losses in the 1st World War (though greatly below that of other nations) was still remembered. The basic attitude was "they're at it again, let them figure it out themselves." To openly support the United Kingdom, the commonwealth nations, France, and all the others for war would quickly become derivesive and be defeated - there was no compelling threat, directly or indirectly, seen, or reasoned to be found, for Germany going against the United States of America.
1. The Treaty of Brest-Liovsk that Germany negotiated with Russia in 1918 was annulled by the Treaty of Versailles. With that treaty void, the borders that were established by it were eliminated, and it now allowed the creation of Poland.
2. The main German battle fleet was never effective in the anti-shipping role. Other than a few sorties, the most famous being the Battle of Jutland in 1916, the fleet was effectively bottled up in German ports throughout the war. Their ineffectiveness is not surprising since the British had broken the German naval code and knew about every sortie before they left the port. Sometimes they knew the whole sailing plan and laid in wait and ambushed the ships - which is how the Battle of Jutland occurred.
3. Germany had warned US boarding passengers about the dangers of sailing to England. Germany actually paid compensation to US citizens killed in the sinking of the ship.
4. The pullback actually affected the campaign that Germany launched against the Soviet Union on June 22, 1941. The extra 100 miles, 6 days of time, that had to be re-conquered from the Soviets played a significant role when the Germans were stopped only 20 miles from the center of Moscow in November 1941.
5. Initially this was a boon. The code was more difficult to crack since the Naval personnel were more adept in changing their base encoding phrase of the day than the German Army counterparts. However, the Naval version was broken (even after it went to four wheels) and since every transmission included the submarines location, they were easily tracked down and sunk. In addition to reading "the mail", radio direction finding equipment allowed instant triangulation of wireless signals to within a mile of a ship's location and that too allowed them to be located and sunk easily.
6. Woodie Guthrie wrote a song about it being sunk on October 31, 1941. The song served to propagandize the sinking to help overcome isolationist feeling.
The "four-piper" USS Reuben James DD-245 of the Clemens class of 1919.
She was torpedoed and sunk by Erich Topp's U-552 on 31 Oct, 1941.