with just a single synchronised Vickers machine gun. On the other hand, the jagdstaffeln were in the process of replacing their early motley array of equipment with Albatros D-series aircraft, armed with twin synchronised MG08s. The D.I and D.II of late 1916 were succeeded by the new Albatros D.III, which was, in spite of structural difficulties, "the best fighting scout on the Western Front" at the time. Meanwhile, most RFC two-seater squadrons still flew the BE.2e, a very minor improvement on the BE.2c, and still fundamentally unsuited to air-to-air combat. This culminated in the rout of April 1917, known as "Bloody April". The RFC suffered particularly severe losses, although Trenchard's policy of "offensive patrol", which placed most combat flying on the German side of the lines, was maintained. During the last half of 1917, the British Sopwith Camel and S.E.5a and the French SPAD S.XIII, all fitted with two forward firing machine guns, became available in numbers. The ordinary two seater squadrons in the RFC received the R.E.8 or the F.K.8, not outstanding warplanes, but far less vulnerable than the BE.2e they replaced. The F.E.2d at last received a worthy replacement in the Bristol F.2b. On the other hand, the latest Albatros, the D.V, proved to be a disappointment, as was the Pfalz D.III. The exotic Fokker Dr.I was plagued, like the Albatros, with structural problems. By the end of the year the air superiority pendulum had swung once more in the Allies' favour. 1918 – the Spring Offensive The surrender of the Russians and the Treaty of Brest-Litovsk in March 1918, and the resulting release of troops from the Eastern Front gave the Germans a "last chance" of winning the war before the Americans could become effectively involved. This resulted in the last great German offensive of the war, the "Spring Offensive", which opened on 21 March. The main attack fell on the British front on the assumption that defeat of the British army would result in the surrender of the mutiny-weakened French. In the air, the battle was marked by the carefully coordinated use of the Schlachtstaffeln or "battle flights", equipped with the light CL class two seaters built by the Halberstadt and Hannover firms, that had proved so effective in the German counter-attack in early October's Battle of Cambrai. The new German fighter aircraft, notably the Fokker D.VII, that might have revived German air superiority in time