The original air aces
The Royal Flying Corps came into being 100 years ago and played a key role in World War I - but who were its heroic pilots and why was the corps so special?
In most accounts of WWI, mention of the Royal Flying Corps goes hand-in-hand with stories of the fighter aces, men like Albert Ball and James McCudden, who downed dozens of enemy planes.
The romance of gladiatorial combat in the air - initially firing revolvers at one another from the cockpit, and then shooting machine guns through the propellers of the aircraft - makes their adventures against such legendary foes as the Red Baron some of the most stirring tales of the Great War.
But as a division of the British Army, the main role of the Royal Flying Corps, with its hundreds of pilots and thousands of ground crew, was very different.
It was the eyes of the army.
For the first time in history, it was possible not only to get a detailed view of the enemy lines from above, but to see what was going on behind those lines - the trench systems, the support routes, the railways and road vehicles that manoeuvred troops and weaponry into position.
The real heroes of the war in the air were the pilots and observers who flew in all conditions to maintain British air superiority, and to keep the ground troops aware of everything that the enemy was doing.
The first five squadrons to arrive in France included one of balloonists, brave men who risked their craft being set on fire or shot down as they were winched into position to survey the enemy. But before long, the fixed wing aircraft took on the main role of reconnaissance.
At first, observers sketched rough maps of what they could see.
But soon two distinct roles developed. One was helping the big guns of the Royal Artillery find their range, flying over the targets and signalling (later sending radio messages) to the gunners to improve the accuracy of their aim.
The other was taking detailed photographs of the trenches. Cumbersome cameras had to be operated over the side of the cockpit, and reloaded at altitude as the aircraft dodged enemy fire.
Initially, planes flew above enemy terrain almost unhindered. But soon enemy aircraft and ground-based anti-aircraft fire made the task more difficult and highly dangerous.
One artillery spotter reported having more than 600 rounds of explosive shells fired at him during a 40-minute crossing and re-crossing of the lines to direct the gunnery.
Despite the appalling noise, and his tiny wood and canvas aircraft being blown about the sky, he and his plane suffered no more damage than a tiny scratch to the upper wing.
The Royal Flying Corps saw the most rapid technological development of flying machinery ever. In 1912, when the corps was formed, its Farman "kites" were not unlike the Wright Brothers' aircraft that had made the first powered flight nine years before.
By the end of the war, large fighters and long-range bombers were the norm, capable of much greater distances - and crucially, they were much more reliable.
Reading the squadron logs, it is heart-breaking how many pilots in the early stages of the war died or were seriously injured by aircraft that suffered mechanical breakdown or crash-landed, even before they got into combat.
The Shuttleworth Collection at Old Warden has one of the world's largest collections of airworthy WWI aircraft, and by today's standards they look terrifyingly flimsy.
It took five men on the ground to keep each pilot in the air, to start the aircraft, and to maintain and repair the planes.
When historian Dan Snow flew in the Avro 504 trainer at the collection, he felt every variation. The plane responded almost like a living thing to slight alterations in wind speed and felt different as it flew over buildings and trees.
What about the airmen themselves?
At the start of the war, pilots had to pay for their own training, and were only reimbursed when they qualified. So initially being a pilot seemed to be a rich man's sport.
But the men who commanded the RFC, Sir David Henderson, Frederick Sykes and Hugh Trenchard, recognised that they needed to train the very best men from all walks of life.
Albert Ball VC and James McCudden VC - two of the most successful fighter aces - both started their careers as ordinary soldiers. And Mick Mannock VC was regarded as a "social misfit".
But all of them excelled in aerial combat, proving that the bravest and most resourceful of pilots could come from any walk of life.
"There was both a fierce personal rivalry and a mutual respect between the aces on both sides," says Snow. "When Albert Ball crashed after defeating the Red Baron's brother, the Germans buried him with full military honours."
By 1918, the RFC had proved its worth to the army. But as Trenchard realised, it was beginning to develop a role for itself that was independent of the army and the navy, namely long-range bombing, far behind enemy lines. As the strategic need for a third, independent force grew, the RFC was subsumed into the new Royal Air Force.