The War Cabinet discussed at some length the action to be taken with regard to Greece. The Chief of the Imperial General Staff explained the military aspects of the question. From a military point of view, he said, it was most desirable not to go to war with Greece, but the present position was intolerable, as the concentration of Greek troops at Larissa threatened the flank and rear of the Allied forces based on Salonica. The Greek army, it was true, was not a formidable one. At the present moment, however, from 15,000 to 20,000 men were concentrated in the neighbourhood of Larissa, and these might be raised to a force of from 50,000 to 70,000 men. The Allied forces in the region of Monastir might, in the near future, be in considerable danger if the enemy released troops from the Roumanian front, which he could now do, to attack in Macedonia. It was, therefore, necessary to take immediate action to remove the danger from the Greek forces. His advice was that we should continue to enforce the blockade until the Greeks had withdrawn all their forces from Thessaly to the Morea. His information was to the effect that the Greeks only had wheat for some three weeks' consumption, including the Morea, and six weeks' stock of petroleum, the stocks of coal being sufficient to last to the end of January, or, with great economy, until the middle of February. Most of these stocks were at the Piraeus, and it was desirable that their distribution should not be permitted. The First Sea Lord pointed out that instructions had been issued to the Vice-Admiral Commanding Eastern Mediterranean to co-operate with the French Commander-in-Chief, and orders had been given him that the mobilisation and concentration of the Greek army towards Larissa should be delayed; that the railway between Larissa and Athens should be attacked by airmen; that ammunition dumps and military stores at Larissa or elsewhere, within reach of aerial attack, should be destroyed by airmen; and that the railway in the vicinity of Mount Olympus, within reach of the sea, should be destroyed by air attack or gun-fire; but that General Sarrail's consent must first be obtained. Unless instructions were sent to the contrary, action might be taken at any moment in execution of these orders.
The Chief of the Imperial General Staff said that instructions had been given to General Milne to assist the Vice-Admiral in any way he could.
The Permanent Under-Secretary of State for Foreign Affairs pointed out the risk that General Sarrail might take such action as would drive us into war at once with Greece. He said that the Greek Government had made a protest against the Allied blockade, and he advised that we should give the Greeks clearly to understand that the blockade would not be removed until they had given reparation for the unjustifiable attack on the Allied troops in Athens. He read a draft reply to the Greek protest, which was discussed.
The War Cabinet were generally averse at this stage to any minor operations, such as raids by aircraft against the Greek communications, which, on the one hand, would only inflict temporary damage, and on the other hand, would actually constitute acts of war. They decided on the following action:-
(1.) The Foreign Office should send a telegram to Greece based on the following principles:-
(a.) The Greek troops in Thessaly should be withdrawn at once to the Morea. Failure to commence the necessary movements within twenty-four hours would be regarded as an act of war.
(b.) Any movement of troops from the Morea northwards would be regarded as an act of war.