This chapter examines the evolution of Royal Flying Corps (RFC) doctrine, policy and practice up to the conclusion of the Somme offensive; capturing the swings of momentum that proved to be the natural rhythm of aerial fighting throughout the First World War. It explores experiences of 1914 and 1915, demonstrating the manner in which considerations relating to control of the air came to be increasingly important to Britain's military aviators. As the Manual stated, '[h]ostile aircraft will be attacked wherever met, in order to prevent the acquisition of information by the enemy, and to gain or retain a moral or material ascendency in the air'. The chapter also explores the RFC's role during the Somme campaign; the first occasion where the Corps was equipped with the aircraft, organisation and wider operational context in which to launch an extended effort to control the air over the Western Front.