<P> The proportion of mustard gas fatalities to total casualties was low; 2% of mustard gas casualties died and many of these succumbed to secondary infections rather than the gas itself . Once it was introduced at the third battle of Ypres, mustard gas produced 90% of all British gas casualties and 14% of battle casualties of any type . </P> <Table> Estimated gas casualties <Tr> <Th> Nation </Th> <Th> Fatal </Th> <Th> Total (Fatal & non-fatal) </Th> </Tr> <Tr> <Td> Russia </Td> <Td> 56,000 </Td> <Td> 419,340 </Td> </Tr> <Tr> <Td> Germany </Td> <Td> 9,000 </Td> <Td> 200,000 </Td> </Tr> <Tr> <Td> France </Td> <Td> 8,000 </Td> <Td> 190,000 </Td> </Tr> <Tr> <Td> British Empire (includes Canada) </Td> <Td> 8,109 </Td> <Td> 188,706 </Td> </Tr> <Tr> <Td> Austria - Hungary </Td> <Td> 3,000 </Td> <Td> 100,000 </Td> </Tr> <Tr> <Td> United States </Td> <Td> 1,462 </Td> <Td> 72,807 </Td> </Tr> <Tr> <Td> Italy </Td> <Td> 4,627 </Td> <Td> 60,000 </Td> </Tr> <Tr> <Td> Total </Td> <Td> 90,198 </Td> <Td> 1,230,853 </Td> </Tr> </Table> <Tr> <Th> Nation </Th> <Th> Fatal </Th> <Th> Total (Fatal & non-fatal) </Th> </Tr> <Tr> <Td> Russia </Td> <Td> 56,000 </Td> <Td> 419,340 </Td> </Tr>

Which army developed tanks first for use during world war i