Hello,
This day 100 years ago was a very active one in the air over the Western Front. I cannot hope to provide a comprehensive account at all, but here are some highlights.
9 July saw the first confirmed victory for René Dorme of Escadrille N3, the original
Cigognes Escadrille. He had already been awarded a 'probable' over an LVG northeast of Compiégne on 11 April, but this was his first confirmed victory. This is a portrait of Dorme by the famous French aviation artist Paul Lengelle.
On the morning of the 9th of April, as the French infantry advanced towards Barleux, Dorme was pursuing an LVG near Péronne, at 0900 hrs. He was flying his Nieuport 16 N939, coded '12' on the aft fuselage. He wrote, "I opened fire at point blank range, five to six meters from the Hun. I saw the observer fall stone dead in his cockpit, and the aircraft spun down." Though it fell in enemy lines it was confirmed. In the evening he attacked another two-seater which went back to its own lines in a glide, and was simply recorded as another 'probable'.

This shows Dorme in the cockpit of N939. On one version of this photo he dated it as 9 July 1916. He considered that he had avenged the wounding of his good friend Joseph Guiget, who had been wounded by a Fokker on 1 July. He wrote, "I avenged him and avenged him well. I was fortunate enough to kill the Hun at my third bullet, and to see him corkscrew down." For his efforts on 9 July, Dorme was proposed for the Médaille Militaire by Capitaine Brocard.
On the same day, at 0900 hrs, SLt
Alfred Heurtaux was also awarded his first confirmed victory over an LVG, near Bertincourt. Jon Guttman says, in fact, that the LVG was a shared victory between Dorme and Heurtaux, but I'm not sure about that. Heurtaux would go on to command the Escadrille and survived the war with 21 victories, though not without being grievously wounded.
Mathieu Tenant de la Tour also scored a victory on 9 July, an EA at Péronne at 2005 hrs.
As for Dorme, he would go on to score 23 confirmed victories and at least 29 'probables'. He was known as
Père Dorme to his comrades, and this nickname adorned his various aircraft.
For those of you wishing to know more about Dorme, I can do no better than to recommend this marvelous, amazing book by Marc Chassard.

"The Air war of Two Aces" interweaves the story of the two friends Dorme and Joseph Guiget, and is written in both fFrench and English. It is wonderfully designed and illustrated, with many rare photos and color profiles. It may be hard to find but it's worth it.
I'm sure Froggy can add more details about Dorme, Heurtaux and Tenant de la Tour!