Complex sentence: Fort Schuyler was dedicated in 1856 after only 75% completion, and was strategically positioned to protect New York City from naval attack through Long Island Sound; guarding the eastern entrance to New York Harbor.
Split into simpler sentences: Fort Schuyler was dedicated in 1856 after only 75% completion. The fort was strategically positioned to protect New York City from naval attack through Long Island Sound; guarding the eastern entrance to New York Harbor.