The Spanish-American war.
. . . but the US was not a neutral nation in world war 2. The US was one of a number of nations that composed the 'Allies' in declaring war on the empire of Japan.
The British Empire
Canada and the US were at war only during the War of 1812. The US was actually at war with the British Empire, but Canada was the closest part of that Empire. Since then Canada and the US have gotten along quite well.
The Americans rebuilt the country for them on the condition that they made sure no more Nazi's were made in Germany.
Sovereignty and independence from the British Empire.
England and her empire
the fight for the ottoman empire
Germany, Austro-Hungarian Empire, Bulgaria, and the Ottoman Empire.
the fight for the ottoman empire
To what end? The US gained no territories as a result of the First World War.
It was called The Central Powers and consisted of the Austria-Hungarian Empire, the Ottoman Empire, Bulgaria and the German Empire.
An empire is an empire, a war is a war.