It was an evident and logical development and in accord with the shortage of national man power and the consequent tendency to a reduction in the strength of the Army, that, the necessary uses of aircraft with the Army and Navy being ensured, any available margin of air power should be employed on an independent basis for definite strategic purposes. The difficulty was to arrive at an agreement as to the minimum tactical and grand tactical requirements of the Army and Navy. The British Army was not alone in asserting that there was no minimum and that it wanted every available airman, and agreed with the French that anything which it could temporarily spare should be lent to the French Army. It was argued that the Armies could as easily and better arrange for strategic bombing. Fortunately in 1918, when I was Chief of the Air Staff, we managed to secure a margin and formed the Independent Air Force in June of that year. It was, of course, understood that, in the event of either the British or French Armies being hard put to it, the Independent Air Force could temporarily come to their direct assistance and act in close co-operation with them. In 1915 in accordance with the old doctrine that offence is the best defence, the surest method of protecting specialized machines on the battle front was found to be in the attack of enemy aircraft by fighting machines. In 1918 it was decided that raids on the centres of German war industry would not only cripple the enemy's output of material essential to victory, but also relieve the pressure on the Western Front, the vital point of the war. The Germans had had the same intention in the many raids which started over Dover on December 21st, 1914. Long-range bombing had, however, been carried out spasmodically before 1918. In addition to its taste for bombing in general, the Royal Naval Air Service were keenly bent from the outset on long-range bombing in particular. The question of forming an Allied squadron to bomb German munition factories was first raised in 1915 at one of the monthly meetings between the French and British Aviation departments; and in February, 1916, a small squadron of Sopwith "1-1/2 Strutters" was formed at Detling for the purpose of bombing Essen and Dusseldorf from England, but the Army in France, being short of machines, asked that they should be sent to the front, and therefore the scheme did not mature; neither, for similar reasons, did one for the co-operation in 1916 of British and French bombing squadrons, operating from Luxeuil.