American public opinion turned against Germany in WW One & WW Two for various reasons.
In WW1, Germany invaded France & Belgium in August 1914. Because, Belgium was a neutral country, Americans were upset with Germany. The invasion of Belgium however was not the most important factor. Later, German unrestricted submarine warfare also turned American public opinion against Germany. Then as a final straw, the German's Zimmermann telegram message to Mexico further angered Americans.
In WW2, Germany invaded Poland, neutral Denmark, neutral Norway, neutral Holland, neutral Belgium, and so forth on & on. German submarine warfare also turned public opinion against Germany.
Belgium was a neutral nation
belgium
Germany against United Kingdom, France and Belgium.
Most likely the attacks by Germany (in either world war) against American civilians and American shipping in the Atlantic Ocean.
The allied invasion of Europe D-day to open a second front against Germany
England and the US were allies in WWII against Germany's invasion of Europe and Africa.
The event that was most influential in turning American public opinion against Germany was the invasion of Belgium.
Belgium was a neutral nation
the German invasion of neutral Belgium
By 1917 the American people became increasingly hostile to Germany. A number of incidents and factors came to head that brought the USA into the war. These all added up the following acts by Germany turned the US against Germany: * Germany's invasion of neutral Belgium; * Germany's policy of unrestricted submarine warfare; * Germany's attempts to sabatoge US industries; and * the perception that Germany tried to involve Mexico in a plot against America.
The Assassination of Arch-Duke Ferdinand Ferdinand's death only explains why Austria and Serbia went to war. Britain came into the conflict against Germany because of Germany's invasion of Belgium.
The invasion of Poland on 1 September 1939 was followed by a declaration of war against Germany by Britain and France two days later.
Germany declared war on France and invaded Belgium. This caused the United Kingdom to declare war on Germany.The time lines of WW1 and 2 can be found in the related links below.
belgium
Mainly the British, with support roles held by Belgium and France.
Germany against United Kingdom, France and Belgium.
Most likely the attacks by Germany (in either world war) against American civilians and American shipping in the Atlantic Ocean.
Britain went to war with Germany because Hitler wouldn't stop his invasion of Poland when the british told him to