<Tr> <Td> 36,000 merchant seamen </Td> <Td> </Td> </Tr> <Tr> <Td> 3,500 merchant vessels </Td> <Td> 783 submarines </Td> </Tr> <Tr> <Td> 175 warships </Td> <Td> </Td> </Tr> <Table> <Tr> <Td> </Td> <Td> This section does not cite any sources . Please help improve this section by adding citations to reliable sources . Unsourced material may be challenged and removed . (July 2015) (Learn how and when to remove this template message) </Td> </Tr> </Table>

Use of sonar in the battle of the atlantic