He used x-ray spectums to determine atomic numbers
'''Henry Gwyn Jeffreys Moseley''' (23 November 1887 to 10 August 1915) was an English physicist. Moseley's outstanding contribution to the science of physicswas the justification from physical laws...
The Gallipoli peninsula on the European part of Turkey during WWI
Born - 23 November 1887 (1887-11-23) Weymouth, Dorset Died - 10 August 1915 (1915-08-11) (aged 27) Gallipoli, Turkey
Henry Moseley died in Gallipoli on August 10th 1915. He was killed by a military conflict. He was 27 years, 8 months and 18 days old when he died.