The History of which this is the first volume is, in the main, the history of the part played in the war by British air forces. It is based chiefly on the records of the Air Ministry collected and preserved at the Historical Section. The staff of the Section have spared no trouble to collect an immense amount of material and arrange it for use, to consult living witnesses, to verify facts down to the minutest details, and to correct any errors that may have crept into the narrative. Their main purpose has been to secure that any statement of fact made in this book shall be true and demonstrable. If in any particular instances they have failed in this purpose, it has not been for lack of pains and care.