Complex sentence: The "CSS-Atlanta" was the first to shoot (about 4.45 a.m.); but this hard-maneuvering ship went suddenly aground, swayed in an awkward angle for shooting.
Split into simpler sentences: The "CSS-Atlanta" was the first to shoot (about 4.45 a.m.). But the hard-maneuvering ship went suddenly aground, swayed in an awkward angle for shooting.