Grey had initially relied on Germany and Britain working together to solve the looming Crisis that occurred when Austria threatened to attack Serbia, just as they had worked together over the Balkan crisis of 1912-1913. However when Germany made it plain that she was not about to bring Austria to the bargaining table, Grey was outraged and realised that a general war was a very real possibility. The British Cabinet had been mainly concerned with the Irish Home rule problems, but their concern about Ireland quickly changed when Austria declared war on Serbia on the 28th July 1914. Grey's main concern was to preserve the balance of power by supporting France; military conversations with France about the British army supporting Fance in the event of war with Germany had been continued for years, although Grey, deviously, had not notified the Cabinet of them. At this stage Grey was not concerned about Belgium at all. The Cabinet was divided about entering the looming war on the side of France so, after August 1st, Grey brought up the possible German invasion of Belgium in an attempt to sway the Cabinet to his way of thinking. Despite this, and despite the British public's desire to support Belgium, there still remained a strong anti-war faction in Cabinet which had became seriously divided. Asquith did not agree with Grey about the reality of the German threat. He did believe that, in the event of war between Germany and France, Germany would invade Belgium but considered that the Treaty of 1839 could be used as a pretext to support Belgium ONLY if Britain found that it was in her interests to support Belgium against an invader. The majority of the Cabinet were unsure, or did not agree, that Germany would attack France via Belgium and agreed to follow Gladstone's 1870 policy of non-intervention; this mood persisted even after the Russian mobilisation. Asquith was not unhappy about this as he was still vacilating. When war between Russia and Germany became inevitable the problem of what to do if Germany invaded Belgium became much more serious. For centuries British policy was that no Great Power should control the Channel Ports. There was also the Anglo-French agreement of 1912 that the British Navy should protect the French coast while the French navy would concentrate in the Mediterranean. On the morning of August 2nd, Lichnowski, the German Ambassador, called on Asquith and made a plea for British neutrality. Asquith replied that Britain would remain neutral as long as Gernany did not violate the Belgian neutrality when attacking France. On that day Cabinet met twice and on the first occasion Grey announced that Britain "... had both moral obligations of honour and substantial obligations of policy in taking sides with France' this caused uproar and the division of Cabinet into war and non-interventionist groups, although with a third undecided group. Asquith was in the undecided camp, he would only enter the war camp if Germany upset the balance of power by invading Belgium or attacked France by using the English channel. When Cabinet resumed in the evening, Germany had invaded Luxembourg and it was obvious that they would invade Belgium. Despite some objections Cabinet agreed that an invasion of Belgium was unacceptable. On 3rd August Grey made his famous speech to the Parliament and warned that Britain's interests and honour would suffer if she allowed Germany to trample on Belgium's neutrality and if she did not come to the aid of France. Britain then sent the ultimatum to Germany on August 4th that unless she vacated Belgium by 11 pm, then Britain "...would be obliged to take all steps in their power necessary to uphold the neutrality of Belgium". There was no German response.... See George Cassar, 1994, "Asquith as War Leader", and Richard Hamilton & Holger Herwig, 2004, "Decisions of War 1914-1917"
13 Days 23 July to 4 August 1914: https://archive.org/details/thirteendaysjuly00arch 4 August 1914 - Parliament of Belgium: https://archive.org/details/augustfourth191400lichrich