It is a great privilege to have been invited to give the 1963 Trenchard Memorial Lecture, and I welcome the opportunity to pay tribute to the memory of a great soldier and airman. Lord Trenchard's deep understanding of the meaning of air power, his single-minded insistence on its proper use, and his dedicated leadership of the Royal Air Force during its formative years, will continue to inspire successive generations of airmen. It is appropriate that the Royal Aeronautical Society's Trenchard Memorial Lecture should be given here at Henlow before an audience of young airmen; for it will be their responsibility to master the new techniques on which will depend the continued evolution of air power.