The USA joined World War I after the Germans sank the Lusitania, a British cruise-liner, containing hundreds of Americans. Their entrance is similar to Belgium's, as they were attacked by Germany. Other countries entered the war for reasons of alliances or reasons of wanting to gain land.
world war one was not fought to end anything in particular. it began when a Serbian nationalist shot Archduke Ferdinand of Austria. this caused Austria-Hungary to declare war on Serbia. Russia, which was allied with Serbia, entered the war, and Germany, allied with Austria-Hungary, also entered. France, which was allied with Russia, declared war on Germany. Italy, allied with Germany, entered the war, and Germany marched through Belgium in order to invade France. Britain, allied with Belgium, declared war on Germany and it's allies, and so forth until the participants extended the world over. the US entered the war because of Germany's use of unrestricted U-boat, or submarine, warfare against neutral nation's merchant fleets.
Germany
When Germany invaded Poland in 1939, France and Britain, who had promised aid to Poland if Germany invaded, entered the war on the Allied side, thus starting the Second World War.
Germany invaded Belgium. Britain had a defense treaty with Belgium. After the invasion, Britain issued an ultimatum stating that if Germany didn't withdraw from Belgium, Britain would declare war. Germany didn't listen and Britain entered World War I.
The US entered the war for a variety of reasons
They didn't? You're thinking of World War II.
They entered because they wanted to EDIT: Czechoslovakia never entered World War II. It was annexed by Germany before the war began.
cigarettes
Germany
Germany wanted revenge after world war 1.
America entered the 1st world war in 1917. it waited till this date for many reasons. when Russia signed a peace treaty with Germany because of the former bolshivik revolution, america entered with the allied powers to balance power. it waited till this date also to be the saver of humanity, as it is claimed america entered the war to save humanity from hitler.I n fact it entered the war to apply the wilsonian world order or what is now known as globalisation to be at the top of the world.
England entered the war when Germany invaded Poland in 1939.
The main reason for the breakout of the world war was that the heir to the austrian-hungary throne was assassinated in Siberia. Austria laid down 10 conditions in front of Siberia which Siberia declined .Germany entered to show their support for Austria and Russia entered for Siberia. The war soon spread throughout Europe and was known as the first world war
The US entered when it declared war on Germany on April 6th 1917. So they entered late.
The United States entered the war in April 1917 on the side of France, Great Britain, & Italy to defeat Germany in November 1918.
When they were attacked by Germany. Very bad choice for Germany.