The main reasons were, America's support the ongoing struggle by Cubans and Filipinos against Spanish rule, and the mysterious explosion of the battleship U.S.S. Maine in Havana Harbor.
The "doctrine of free will" blended easily with political ideas about democracy and independence because it taught people that their actions would have consequences.
The Siege of Vicksburg was important to the Union troops because they were able to take control of the Mississippi River. This allowed the Union troops to cut the Confederacy in half and allowed the Union to cut of supplies/resources to Confederate states.
The Battle of Gettysburg was an important Union win because this was the last time in the Civil War that the Confederate troops truly invaded the North. After this battle they did not invade any state north of Pennsylvania.
. . . that would be a <u><em>clipper ship</em></u>
this would be a larger vessel meant for traveling long distances quickly & smoothly resulting from it's construction using a narrow/streamlined body & large sail spread to catch the wind.
