Complex sentence: After the war he returned to the merchant marine, where he remained for twelve years, and in 1786 commanded one of the first American ships to engage in trade with China, the "Canton", operating from Philadelphia.
Split into simpler sentences: After the war he returned to the merchant marine, where he remained for twelve years. In 1786 he commanded one of the first American ships to engage in trade with China, the "Canton", operating from Philadelphia.