an Austrian plane was shot down with ground-to-air fire, as well as the first medical evacuation by the Serbian army in autumn 1915. German Offensive in Belgium and France Upon mobilisation in 1914, 80% of the German Army was located on the Western Front, with the remainder acting as a screening force in the East; officially titled Aufmarsch II West, it is better known as the Schlieffen Plan after its creator, Alfred von Schlieffen, head of the German General Staff from 1891 to 1906. Rather than a direct attack across their shared frontier, the German right wing would sweep through the Netherlands and Belgium, then swing south, encircling Paris and trapping the French army against the Swiss border. Schlieffen estimated this would take six weeks, after which the German army would transfer to the East and defeat the Russians. The plan was substantially modified by his successor, Helmuth von Moltke the Younger. Under Schlieffen, 85% of German forces in the west were assigned to the right wing, with the remainder holding along the frontier. By keeping his left wing deliberately weak, he hoped to lure the French into an offensive into the "lost provinces" of Alsace-Lorraine, which was in fact the strategy envisaged by their Plan XVII. However, Moltke grew concerned the French might push too hard on his left flank and as the German Army increased in size from 1908 to 1914, he changed the allocation of forces between the two wings from 85:15 to 70:30. He also considered Dutch neutrality essential for German trade and cancelled the incursion into the Netherlands, which meant any delays in Belgium threatened the entire viability of the plan. Historian Richard Holmes argues these changes meant the right wing was not strong enough to achieve decisive success and thus led to unrealistic goals and timings. The initial German advance in the West was very successful and by the end of August the Allied left, which included the British Expeditionary Force (BEF), was in full retreat. At the same time, the French offensive in Alsace-Lorraine was a disastrous failure, with casualties exceeding 260,000, including 27,000 killed on 22 August during the Battle of the Frontiers. German planning provided broad strategic instructions, while allowing army commanders considerable freedom in carrying them out at the front; this worked well in 1866 and 1870 but in 1914, von Kluck used this freedom to disobey orders, opening a