Which factor shift american opinion away from neutrality during world war 1

The factor is strong cultural ties to Great Britain.
Back than, our country was determined to stayed out of the war for almost 2 years. Because of this, Germany started to gained upperhand to the nations that we considered as our close ally, such as Great Britain and France.
We saw that the attack made by Germany as an attack to human liberty because they tried to change it into their fascist government, so we eventually decided to join  the war.