He proposed that the pair attack the Red Baron's squadron at its airfield at dawn, catching the German pilots off guard. Bishop agreed to take part in the daring scheme at the end of the month, after he returned from his forthcoming leave. That night, in his last letter to his father, Ball wrote "I do get tired of always living to kill, and am really beginning to feel like a murderer. Shall be so pleased when I have finished". Final flight and aftermath On the evening of 7 May 1917, near Douai, 11 British aircraft from No. 56 Squadron led by Ball in an S.E.5 encountered German fighters from Jasta 11. A running dogfight in deteriorating visibility resulted, and the aircraft became scattered. Cecil Arthur Lewis, a participant in this fight, described it in his memoir Sagittarius Rising. Ball was last seen by fellow pilots pursuing the red Albatros D.III of the Red Baron's younger brother, Lothar von Richthofen, who eventually landed near Annœullin with a punctured fuel tank. Cyril Crowe observed Ball flying into a dark thundercloud. A German pilot officer on the ground, Lieutenant Hailer, then saw Ball's plane falling upside-down from the bottom of the cloud, at an altitude of , with a dead prop. Brothers Franz and Carl Hailer and the other two men in their party were from a German reconnaissance unit, Flieger-Abteilung A292. Franz Hailer noted, "It was leaving a cloud of black smoke... caused by oil leaking into the cylinders." The engine had to be inverted for this to happen. The Hispano engine was known to flood its inlet manifold with fuel when upside down and then stop running. Franz Hailer and his three companions hurried to the crash site. Ball was already dead when they arrived. The four German airmen agreed that the crashed craft had suffered no battle damage. No bullet wounds were found on Ball's body, even though Hailer went through Ball's clothing to find identification. Hailer also took Ball to a field hospital.Pengelly. Albert Ball VC: The Fighter Pilot Hero of World War I. pp. 196–97. A German doctor subsequently described a broken back and a crushed chest, along with fractured limbs, as the cause of death. The Germans credited Richthofen with shooting down Ball, but there is some doubt as to what happened, especially as Richthofen's claim was for a Sopwith Triplane, not an S.E.5, which is