The reasons for the US involvement of World War I, one of them was from the German invasion of Belgium, Germany declared war on France. To avoid the French fortifications along the French-German border, the troops had to cross Belgium and attack the French Army by the North. Of course, Belgians refused to let them through, so the Germans decided to enter by force and invaded Belgium on August 4, 1914. Another reason the US was involved because of American loans, and the only thing they try to get was in the hope that they would mobilize large sums of money from the public, governments publicized the war loans as patriotic contributions to the war effort, a financial substitute for serving in the field. Last but not least, they also enter the war for unrestricted submarine warfare as the practice of using submarines to attack and sink all forms of enemy shipping, whether they are military or civilian. It is most closely associated with World War I when Germany's decision to use USW brought the US into the war and led to their defeat.
