Complex sentence: Also, the "Atlanta"-class was the only class of World War II American cruisers to be armed with a battery of torpedoes, for surface combat; acoustic torpedoes for attacking submerged submarines did not exist until later in the war.
Split into simpler sentences: Also, the "Atlanta"-class was the only class of World War II American cruisers to be armed with a battery of torpedoes. Initially, they could only be used against surface vessels, as acoustic torpedoes for attacking submerged submarines were not available until later in the war.