Question

Confederate ships that broke through the North's line of defense were called a. schooners. c. clippers. b. ironsides. d. blockade runners.

Answer 1

They were called BLOCKADE RUNNERS.
The American civil war occurred between 1861 and 1865. The ships that were used by the confederate state navy during this period were called confederate ships. There are different types of ships used for different war purposes. Blockade runner ships were usually used to evade the naval blockade set up at  ports, typically in order to bring supplies to a blockade town.

Answer 2

The answer is D: Blockade Runners