October 1941. The idea was short-lived and he was not to remain there long, as on 16 March 1942 Crocker was promoted to the acting rank of lieutenant-general and was given command of XI Corps, taking over from Lieutenant-General Noel Irwin, who was being posted to command IV Corps in the Mediterranean theatre. Aged just forty-six, this made Crocker one of the youngest corps commanders in the British Army. It is quite probable that Alan Brooke, who still thought highly of Crocker and was now Chief of the Imperial General Staff (CIGS), secured for him his new appointment. Crocker's new command, which had Harold Morgan's 45th, Evelyn Barker's 54th (East Anglian) and Eric Miles's 56th (London) Infantry Divisions, along with the 21st Army Tank Brigade, under command, was based in East Anglia, where it had responsibility for its defence in the event of an invasion, and was serving under Eastern Command. North Africa Again, Crocker's appointment was not destined to last long as, in September, he relinquished command of XI Corps over to Lieutenant-General Gerard Bucknall, and took command of IX Corps District from Lieutenant-General Francis Nosworthy. The corps, with Gordon MacMillan (later a distinguished divisional commander and full general) as its Brigadier General Staff (BGS), was then stationed in Northern England under Northern Command, with responsibility for Durham, Northumberland, and the North Riding of Yorkshire. Crocker's rank of major-general was made permanent on 4 December 1942 (with seniority backdated to 16 November 1941). On 16 March 1943 his rank of lieutenant-general was made temporary. In September IX Corps District was mobilised to become a field force formation, was redesignated as IX Corps once again, and was assigned to the newly created British First Army. Commanded throughout its existence by Lieutenant-General Kenneth Anderson, the First Army was formed to be the parent formation for the Allied forces preparing to invade French North Africa as part of Operation Torch. Lieutenant-General Charles Allfrey's V Corps formed the other half of the British contingent of the First Army and saw bitter fighting in the early stages of the Tunisian campaign towards the end of 1942 and in early 1943. Together with his corps HQ, Crocker departed for North Africa in the spring of 1943, with his HQ becoming operational on 24 March 1943. He took under command his old 6th Armoured Division, now under Major-General Charles Keightley, along with the 46th Infantry Division,