The Royal Air Force is 90 years old. It was formed from the merger of the Royal Flying Corps and the Royal Naval Air Service on 1 April 1918 (yes, April Fool’s Day), as the result of an Act of Parliament. This was historic. The RAF may not have been the world’s first independent air force to become independent of military or naval control: the Finnish Air Force apparently beat it by less than a month. But as the FAF started out with just one aeroplane (and that liberated from Sweden), and the RAF with thousands, the British experiment was the riskier. Particularly given that - by chance - it came in the middle of a massive German offensive on the Western Front.

The British example was assuredly more influential than the Finnish, too. Most air forces around the world are now independent, though the fashion took a while to catch on. The Dominion air forces mostly became independent in the 1920s, as did Italy’s; France and Germany followed in the 1930s; the US and Japan fought the Second World War without an independent air force.

I’ve never been able to form a clear picture of just how smoothly the merger between the RFC and RNAS went. One would expect there to be some problems in integrating branches from two services with very different traditions, cultures, routines, doctrines, equipment and so on, but it doesn’t seem to have been much of a problem. There were some longer-term issues - in 1922, P. R. C. Groves complained about former naval men on the Air Staff, who didn’t understand the RAF’s unique needs, and equally complained that the RAF still had an Army mindset. This was, at least partly, a dig at Hugh Trenchard, a late convert to the idea of an independent air force. Trenchard had always been devoted to the Army’s needs during the war, and in Groves’s view, at least, had obstructed the work of the Independent Force while its commander in 1918.

Since the RFC was much larger than the RNAS, this was probably inevitable to start with. Certainly for the first few years of its existence, the RAF had Army-style ranks, and allowed its officers to wear their RFC khaki uniforms until they wore out – which they were probably keen to do, as the first RAF uniform was a very unpopular pale blue.

In 1919 the RAF adopted its own rank structure, actually more reminiscent of the Navy’s - “flight-lieutenant” came directly from the RNAS, where it was a simple modification of the equivalent rank of “lieutenant”; “group captain” is equivalent to the Navy’s “captain”, and both are much higher in rank to the Army’s “captain”.

Of course, the senior services were jealous of their new sibling: there was a concerted attempt to smother it in 1921. This failed, but eventually the idea that the air was indivisible was eroded. The Fleet Air Arm became part of the Navy in 1937, partly undoing the unification of 1917. And in the Second World War, the Army began to acquire some air assets too: twelve squadrons of observation aircraft and a fleet of gliders come to mind.

So, why was the RAF formed at all? The proximate cause, at least, can be traced to Jan Smuts, the South African field marshal who was a member of the Imperial War Cabinet (IWC). After the shocking Gotha air raids on London in June and July 1917, Smuts was tasked with coming up with proposals for dealing with the threat of the bomber. He wrote two reports: the first argued that a co-ordinated air defence system was needed to protect the capital; the other was more far-sighted, and tried to anticipate the future development of airpower, predicting that a time would come when aircraft would operate independently of armies and navies, in potentially decisive fashion, and that there therefore was a need for an air force independent of both of the older services.

In other words, in order to effectively carry out strategic bombing of Germany, a mission which had little to do with the objectives of the Army and Navy, an independent air force was needed. So, the standard picture of the RAF?s formation involves a Cabinet shaken by public anger over the bombing of London, its need to be seen to be doing something in response, and coming up with the idea of the independent air force.

The other, more revisionist view is that the formation of the RAF was more about solving the problem of allocating aircraft and engine production between the RFC and the RNAS than a visionary attempt to create a strategic air weapon. This is suggested by Eric Ash in his excellent book on Frederick Sykes, the Chief of the Air Staff (i.e., head of the RAF) for most of 1918. The promised bounty of massive American aircraft production, Ash argues, was an incentive for the British to get their act together, lest it went to Italy instead, who the Americans were working with closely. Ash doesn?t go so far as to actually deny that the desire for some sort of aerial reprisals against Germany was an important factor. Actually, he?s more concerned to rebut the charge that the RAF was therefore a bad idea, as not much was achieved in the way of strategic bombing. Still, he thinks that the American connection has been overlooked by historians, as it doesn?t appear in the Smuts reports.

Which view is correct? It’s not a subject I’ve specifically worked on, so I’m going to sit on the fence and say it’s probably a bit of both. Ash doesn’t really support his argument with primary sources very strongly, to my mind, perhaps because it’s slightly out of the way for him (Sykes was not involved in the creation of the RAF). The Smuts reports are the key documents in the founding of the RAF, because it was they which convinced the IWC to go for the unified air service, so Ash needs to explain why it is that Smuts or the IWC didn?t talk about American aircraft production, if this was so important.

That the the RAF was primarily a response to the German bombing of London is supported by the fact that, after agreeing to its foundation in late August 1917, the IWC then began to have second thoughts. This is because the panic over the daylight Gotha raids was subsiding. It was only after the nighttime Gotha raids began, in late September 1917, that the IWC pushed on with forming the RAF. At the same time, rationalising production was certainly a concern of many of those who, like Montagu of Beaulieu, publicly called for the creation of an “Royal Air Service”.