The first phase of the British offensive on the Western Front came to an end yesterday, and gave RFC command a chance to consider the operation so far. The weather had severely restricted air work, but what had been possible had shown that a change of tactics was desirable. The offensive patrols had too often passed without incident, and it seemed clear that the enemy had, at least temporarily, ceased to fly at great heights. A memorandum, issued from the Royal Flying Corps headquarters on the 15th of April, stated:
“The enemy seems for the moment to have given up, to a certain extent, his method of depending entirely upon height, and his machines and formations are undoubtedly slipping underneath our high patrols without being seen by them. His tactics are of course rendered easier by the cloud layer which, even on fine days, has extended of late somewhere between 5,000 and 7,000 feet. By coming up through or underneath these clouds his machines have on several occasions attacked our photographic and artillery machines unseen by our scouts ‘although large numbers of the latter have been in the area at the time. High patrols must be maintained, otherwise the enemy will undoubtedly adopt his former tactics once again, but they often miss an opportunity through being too high. It must be remembered that the conditions which favour this form of attack by the enemy apply equally in our own case, and that low patrols working under or through the clouds should obtain many opportunities of acting by surprise. While therefore the G.O.C. is very strongly opposed to anything in the nature of a local escort of scouts, he would like Brigadiers to consider carefully the advisability of working some of their patrols at or about the height at which the Corps machines are working, with high patrols up at the same time.”
The Germans it seems were on the defensive and outnumbered. Under instructions from the Supreme Army Command, the majority of single-seater fighters were sent up only when the Royal Flying Corps was most active. Special air protection officers (Luftschutz Offiziere) were stationed well forward to watch and report on the movements of the Royal Flying Corps aeroplanes. Based on their reports the air commanders at the various corps headquarters judged whether to bringing their fighting aeroplanes into action.