<Tr> <Td> April 9--May 17 </Td> <Td> Second Battle of Arras . The British attack a heavily fortified German line without obtaining any strategic breakthrough . </Td> <Td> Details </Td> </Tr> <Tr> <Td> April 9--12 </Td> <Td> The Canadians obtain a significant victory in the Battle of Vimy Ridge, part of the first phase of the Second Battle of Arras . </Td> <Td> Details </Td> </Tr> <Tr> <Td> April 9--14 </Td> <Td> First Battle of the Scarpe, part of the first phase of the Second Battle of Arras . </Td> <Td> Details </Td> </Tr> <Tr> <Td> April 10--11 </Td> <Td> First Battle of Bullecourt, part of the first phase of the Second Battle of Arras . </Td> <Td> Details </Td> </Tr>

After austria hungary declared war on serbia russia