Complex sentence: In February 1861 the Confederate Navy had thirty ships, only fourteen of which were seaworthy, while the Union Navy had ninety vessels; the C. S. Navy eventually grew to 101 ships to meet the rise in naval threats and conflicts.
Split into simpler sentences: In February 1861 the Confederate Navy had 30 vessels, only 14 of which were seaworthy. The C. S. Navy eventually grew to 101 ships to meet the rise in naval threats and conflicts.