 Throughout the Industrial Revolution , Plymouth grew as a commercial shipping port , handling imports and passengers from the Americas , and exporting local minerals ( tin , copper , lime , china clay and arsenic ) while the neighbouring town of Devonport became a strategic Royal Naval shipbuilding and dockyard town . In 1914 three neighbouring independent towns , viz . , the county borough of Plymouth , the county borough of Devonport , and the urban district of East Stonehouse were merged to form a single County Borough . The combined town took the name of Plymouth which , in 1928 , achieved city status . The city 's naval importance later led to its targeting and partial destruction during World War II , an act known as the Plymouth Blitz . After the war the city centre was completely rebuilt and subsequent expansion led to the incorporation of Plympton and Plymstock along with other outlying suburbs in 1967 . 
