On the 1 April 1918 the Royal Flying Corps and Royal Naval Air Service merged to form the Royal Air Force. Since there were a significant number of women working in both of those organisations there was a need for a separate women’s air service so the Women’s Royal Air Force was also formed on the same date. There have been a number of celebrations of this particular centenary and the RAF have helpfully created their own web page detailing all of them, which you can find here: https://www.raf.mod.uk/our-organisation/raf100/
However April 1918 saw another air related act which probably felt much more significant to those fighting on the Western Front at the time then then changing names of the organisations they were serving in – the death of the Red Baron, one of the deadliest pilots of WWI.
Not that anyone at the time would have referred to Manfred von Richthofen as the Red Baron, no one is sure where the epithet came from and it wasn’t used during his life time.
In his own diaries he refers to himself as the der rote Kampfflieger (the red fighter pilot) and the French used the term Le Diable Rouge (Red Devil) which is understandable given that by the time he was shot during a dogfight on 21 April 1918 he was responsible for bringing down 80 Allied aircraft whilst flying his incredibly distinctively painted Fokker DR1
There is an excellent overview of Richthofen’s life and death on The German Way & More website here, including a paragraph on the circumstances of his death which I quote verbatum below:
On April 21, 1918 Richthofen flew off with nine other planes from the airfield at Cappy, France. Soon the German fliers were in combat with a squadron of RAF Sopwith Camels led by the Canadian pilot Arthur Roy Brown. At some point during this battle Richthofen was pursuing a plane piloted by a novice Canadian pilot named Wilfrid May. When Richthofen flew across the British lines at low altitude, he was struck by a single bullet and fatally wounded. Before he died, he managed to land his red Fokker Dr.1 triplane just north of the village of Vaux-sur-Somme, in a sector controlled by Australian forces. Still intact, the Red Baron’s bright red plane was soon dismantled by souvenir seekers.https://www.german-way.com/notable-people/featured-bios/manfred-von-richthofen/
And I found this rather delightful photo of him, in 1916, petting his dog Moritz, on the rare historical photos website here: