This chapter will consider the final developments in the Franco-British command arrangements following the politicians' gropings towards unity of command at the end of 1917 and beginning of 1918 just described. Those developments had been essentially political and British-inspired – Clemenceau saw little value in the SWC. However, the final stage in the command relationship was not a political but a military solution, prompted by a military crisis – the German forces on the Western Front, increased in number by divisions returned from the east, using extravagant and ultimately futile tactics, smashed Haig's complacency and his Fifth Army during the days following 21 March 1918. It is necessary to be selective here, for the final victorious campaigns still await a thorough study. Here I leave the fighting on one side, looking only at the mechanics of the unified arrangements for command and the attitude of the participants to unity of command. Only by taking into account attitudes can the mechanism's efficiency – the output measured against the input and the losses through friction – be understood.

Before the first German spring offensive began on 21 March 1918 and provoked the final crisis of the war, the French and British commanders-in-chief had defeated by private agreement the attempt to impose political control over military actions in the person of the president of the Supreme War Council's Executive War Board, General Ferdinand Foch.