In the days before the
Battle of the Somme, Trenchard ordered that reconnaissance sorties be flown and German observation kite balloons be targeted. On the eve of battle, Trenchard had mustered 105 aircraft to the rear of the
Fourth Army and with the commencement of the battle, Trenchard brought his squadrons systematically into action. Low-level bombing was a major task for the participating aircraft and many were shot down. Despite the losses, by mid-August the Flying Corps had succeeded in gaining
air supremacy in the skies over the Somme. However, by September 1916 the prospects of a German collapse were remote and Trenchard feared that the Flying Corps in its weakened state was vulnerable to a German recovery in the air. Trenchard appealed to the War Office and even to the Admiralty for replacements in number but these were not initially forthcoming. By mid-September the
German Air Service had regained some strength and Flying Corps began to take casualties in greater numbers. The Flying Corps' decline in numbers impaired their ability to provide accurate artillery support and although in late October a naval squadron was provided from
Dunkirk, the British remained weak in the air. After the conclusion of the Battle of the Somme, Trenchard's Flying Corps remained in a weakened state and all along the
Front, Trenchard's aircraft were still fighting those of the German Air Service. In November 1916, Haig, on Trenchard's urging, sought a further 20 squadrons of fighters and in December, Trenchard travelled to London to appeal in person for additional fighters. With his words failing to produce the desired aircraft, Trenchard repeatedly wrote to Henderson and Brancker and when Trenchard went over Henderson's head to the President of the Air Board
Lord Cowdray, Henderson severely reprimanded him. While the winter weather gave some respite from the struggle in the air, the appearance of better weather in March 1917 brought a fresh offensive from the German Air Service. Trenchard was forced to cut back his offensive activity to a minimum although he continued to provide support to the British infantry as they slowly advanced to the
Hindenburg Line. In April the Flying Corps supported the infantry as best it could during the
Battle of Arras and engaged the Germans in a fierce air battle, known as
Bloody April, in the skies overhead. Overall, from March to May, Trenchard lost 1270 aircraft and coupled with the production crisis in Great Britain this almost resulted in the destruction of the Flying Corps. By mid-1917
William Weir's actions in getting British aircraft production working had started to bear fruit. The newly supplied
S.E.5s,
Bristol Fighters and
de Havilland 4s enabled Trenchard to dominate the airspace along the Front before and during the
Battle of Messines. Although the Flying Corps' reserves remained low, Trenchard and his staff were then able to begin planning for Haig's upcoming offensive at
Ypres. ==Bombing raids on London==