explicitly threatening to resign if he acted on Briand's impassioned plea to send more divisions to Salonika. A further Conference followed in London (15–16 January 1917). Cadorna was also once again talking of being able to win a major victory if reinforced by 300 heavy guns or 8 British divisions – Robertson predictably opposed this (29 January). Calais Haig wanted to delay his attack until May to coincide with Italian and Russian attacks, but was told by the government to take over French line as requested, to live up to both the "letter" and "spirit" of the agreement with the new French Commander-in-Chief Nivelle, to be ready no later than 1 April, and not cause delays, almost certainly a result of private lobbying by Nivelle. Robertson was worried about Nivelle forcing the British to attack before the ground dried, although when Haig blamed the poor state of the railways (he demanded twice the railway requirements for half as many troops as the French), he inquired (28 January) whether Haig's staff had obtained an exaggerated figure by simply adding together the highest estimate of every subordinate formation. Haig demanded a meeting between British and French ministers to resolve matters, although Robertson urged him (14 February) to resolve them in a face-to-face meeting with Nivelle and keep the politicians out of it. Robertson later claimed that he attended the Calais Conference thinking it would be solely about railways, but this is probably untrue. Robertson was at the War Cabinet (20 February) – he told them that Haig and Nivelle were in complete agreement – which insisted on a conference to draw up a formal agreement about "the operations of 1917", and Robertson wrote to Haig (24 February) informing him of this. Neither Robertson nor Derby were invited to the War Cabinet on 24 February (no minutes were circulated, but on the train to Calais Hankey was instructed to draw up a summary to be circulated after the conference), at which ministers felt that the French generals and staff had shown themselves to be more skilful than the British, while politically Britain had to give wholehearted support to what would probably be the last major French effort of the war. Hankey also told Stamfordham that on the train to Calais Lloyd George had informed Robertson and Maurice that he had the authority of the War Cabinet "to decide specifically between Generals Haig &