Complex sentence: In 1818 "Amphion" sailed to Brazil and in 1820 she was decommissioned and in November that year she was sunk as a breakwater at Woolwich.
Split into simpler sentences: In 1818 "Amphion" sailed to Brazil and in 1820 she was decommissioned. In November 1820 year she was sunk as a breakwater at Woolwich.