 Complete the following phrase:  At the outbreak of World War I on 2 August 1914, von Kuhl became Chief of Staff in General Alexander von Klucks First Army which was the crucial right flank of the swinging door in the Schlieffen Plan. Kluck regarded him as a notable man, of most energetic character and wide views. Mentally and physically he was imperturbable, and, in addition to an extremely cultivated mind, he possessed a personal bravery on the battlefield which from time to time evoked a caution from the Army Commander. By adroit staff planning they squeezed their 320,000 men through a strip of land between Liege and the Dutch border. Pivoting down into France they swept back the British Expeditionary Force. Shortly thereafter they had reached the 