Nearly 450,000 service records of members of the Royal Flying Corps and the Royal Air Force have been released by the National Archives, including 342,000 never seen before online.
The records, recently digitised by family history website Findmypast, reveal the history of the Royal Air Force in the First World War - from the first aerial troops in 1899, through the war and into World War II.
The records contain information about their peacetime and military career, as well as physical descriptions, religious denominations, family statuses and photographs.
Many date from 1912 with the formation of the Royal Flying Corps (RFC) and include men who continued to serve in the RAF until 1939.
More than 58 nationalities served in the RAF during the First World War, with men signing up from as far afield as India, Brazil, Japan, and Russia, the records show.
The records have been unveiled to mark the centenary of the First World War.