Belgium had been recognised in the Treaty of London (1839) as a sovereign and neutral state after the secession of the southern provinces of the Netherlands in 1830. The German invasion of Belgium on 4 August 1914, in violation of Article VII of the treaty, was the British against Germany. British military operations in Belgium began with the arrival of the British Expeditionary Force (BEF) at Mons on 22 August. Operations in Flanders began during the Race to the Sea, reciprocal attempts by the French and German armies to turn their opponents' northern flank, through Picardy, Artois and Flanders. On 10 October, Lieutenant-General Erich von Falkenhayn, the Chief of Staff of the (OHL, supreme army command), ordered an attack towards Dunkirk and Calais, followed by a turn south behind the Allied armies, to gain a decisive victory. On 16 October, the Belgians and some French reinforcements began the defence of western Belgium and the French Channel ports, at the Battle of the Yser. When the German offensive failed, Falkenhayn ordered the capture of Ypres to gain a local advantage. By 18 November, the First Battle of Ypres had also ended in failure, at a cost of casualties. In December, the British Admiralty began discussions with the War Office, for a combined operation to re-occupy the Belgian coast but were obliged to conform to French strategy and participate in offensives further south.