The strategies used by the Union during the Civil War included:
-
naval blockade: The Union implemented a naval blockade to restrict the Confederacy's trade and supplies.
-
seizing control of the Mississippi River: One of the Union's key strategies was to gain control of the Mississippi River to cut the Confederacy in two and control transportation routes.
The other options, defensive war and relying on European countries for supplies, were not strategies primarily employed by the Union. The Union was more on the offensive, seeking to defeat the Confederate forces, and while there was some hope that European powers might support the Confederacy, the Union did not rely on Europe for supplies in the same way the Confederacy did.
So the correct options are:
- naval blockade
- seizing control of the Mississippi River