A collection of photos capturing the development of the Royal Air Force (RAF) across the decades has been released to mark the centenary of the world's first independent air force.
It was 100 years ago on April 1, 1918, that the Royal Flying Corps and the Royal Naval Air Service merged to create the Royal Air Force.
At the outbreak of the First World War in August 1914, the Royal Flying Corps had 146 officers and around 100 aircraft, while the Royal Naval Air Service had over 700 personnel, 93 aircraft, two balloons and six airships.
By the end of the war in November 1918, the Royal Air Force had grown in strength to 27,000 officers and 260,000 other personnel operating more than 22,000 aircraft.
To celebrate the 100th anniversary, the Ministry of Defence (MoD) has collated and released 100 images - including early shots, aerial views of Mosul in the 1920s, through to the Second World War and Cold War.
The pictorial history also includes images from the RAF's most recent operations and equipment such as the F-35 stealth fighter jet, as well as never-before-seen photos.
The Latin motto of the RAF, "Per ardua ad astra", translates to English as "through adversity to the stars".
Soon after its creation the force again made history, when, in 1919, a converted out-of-service RAF Vickers Vimy heavy bomber, a type of aircraft used during the First World War, was flown by former RAF pilots Captain John Alcock and Lieutenant Arthur Whitten-Brown from Newfoundland to Galway, Ireland, on the first non-stop transatlantic flight.
Another key moment in the RAF's history was the Battle of Britain in the Second World War.
It was the first major battle to be fought entirely by air and was a critical factor in preventing a Nazi invasion of Britain.
The Battle of Britain lasted from July 10, to October 31, 1940, and saw the RAF's 1,200 fighter and bomber planes pitted against the Luftwaffe's 3,000.
The RAF victory led to Winston Churchill's famous remark that "never in the history of human conflict has so much been owed by so many to so few".
The British-designed Harrier Jump Jet entered RAF service in 1969, making the RAF the first in the world to use its revolutionary vertical take-off and landing capabilities.
The idea behind the plane was that if World War Three did break out, there would be nuclear devastation, and aircraft would be required that could take off without a runway, and be placed or hidden anywhere.
Figures show that as of April 2017 there were 828 RAF aircraft - a figure which includes tri-service training aircraft.
As of January 2018 there were more than 36,963 service men and women in the RAF - both regular and reserves.