Shire and Petain's collaboration was not for Nivelle.
Nivelle's appointment as the commander-in-chief was already decided, he had the support of the British, and the British had a large amount of materials loaned from the United States. This alone was enough to influence the choice of the commander-in-chief.
At the same time, after Nivelle became commander-in-chief, the decisions he made were not something that Shire and commanders at Petain's level could change. Above them were a group of vice admirals, they were the ones discussing strategic directions, not major generals like Shire and Petain.
Shire did this to combat parliament, he believed that parliament was the troublesome opponent.
Parliament had the decision-making power and was now relentlessly weakening Shire's influence, consciously grooming "enemies" to divide and rule.
