Mobilisation In February 1939 the existing AA defences came under the control of a new
Anti-Aircraft Command. In June a partial mobilisation of TA units was begun in a process known as 'couverture', whereby each AA unit did a month's tour of duty in rotation to man selected AA and searchlight positions. On 24 August, ahead of the declaration of war, AA Command was fully mobilised at its war stations. The outbreak of World War II saw 58 AA Battalion forming part of
40th Anti-Aircraft Brigade in
2nd AA Division. Based at
RAF Duxford, the brigade was responsible for providing AA defence for RAF airfields in
East Anglia. In April 1940, 58th moved to come under the command of
39 AA Bde.
Battle of Britain and Blitz On 1 August 1940 the Royal Engineers' AA battalions were transferred to the
Royal Artillery (RA), being redesignated searchlight regiments, and the companies became batteries. By this time 58th (Middlesex) had been moved to
32nd (Midland) Anti-Aircraft Brigade, still in 2 AA Division, but now responsible for AA defence of the East Midlands during the forthcoming
Blitz. A new 511 S/L Bty was formed for the regiment in late 1940. Initially it was attached to the
40th (Sherwood Foresters) S/L Rgt and remained in 39 AA Bde, coming under command of
30th (Surrey) S/L Rgt from 8 January (when it was considered operationally active) until 12 May 1941, when it rejoined 58th S/L Rgt. The regiment also supplied a
cadre of experienced officers and men to 233rd S/L Training Rgt at
Saighton Camp where it provided the basis for a new 539 S/L Bty formed on 12 December 1940. This battery later joined a newly forming
88th S/L Rgt.
344th Battery On 19 April 1943, 344th Bty received orders to train for a mobile role, and after this training it joined 100 AA Bde on 30 June. 100 AA Bde was one of the formations slated to participate in
Operation Overlord (the Allied invasion of Normandy planned for 1944) and shortly afterwards the battery became formally independent of 58 S/L regiment. 344th Independent S/L Bty proceeded to Normandy in July 1944 where it pioneered the use of searchlights to create artificial moonlight, otherwise known as movement light or 'Monty's Moonlight', to aid movement in night operations by 21st Army Group. In February 1945 it changed its title to 344th Independent Moonlight Bty and split off a separate 581st Independent Moonlight Battery.
Operation Diver Meanwhile, the rest of 58th S/L Regt (425 and 426 Btys) had remained with AA Command. In May 1944 it was joined by 314 (Kent) S/L Bty from
29th (Kent) S/L Rgt. Then on 1 June E Troop of 372 S/L Bty of
43rd (5th Duke of Wellington's Regiment) S/L Rgt joined and became E Trp of 425 S/L Bty. The most severe phase of V1 attacks on the UK ended in September 1944 after the launching sites were overrun by the advance of
21st Army Group along the coast of France and Belgium.
Infantry role By the end of 1944, the German
Luftwaffe was suffering from such shortages of pilots, aircraft and fuel that serious aerial attacks on the
United Kingdom could be discounted and the
War Office began reorganising surplus anti-aircraft regiments in the UK into infantry battalions for duties in the rear areas. 58th Searchlight Regiment was one of the units selected for conversion, and on 9 November 1944 it was ordered to convert, being redesignated
58th (Middlesex) Garrison Regiment, RA. (314 Searchlight Bty became independent and eventually rejoined 29th S/L Rgt.) Meanwhile,
21st Army Group fighting in
North West Europe was suffering a severe manpower shortage, particularly among the infantry. In January 1945, the War Office accelerated the conversion of surplus artillery into infantry units, primarily for line of communication and occupation duties, thereby releasing trained infantry for frontline service. 58 Garrison Regiment was redesignated again, becoming
611 (Middlesex) Infantry Regiment, RA in February. It went to North West Europe the following month and did duty with
Second Army until after
VE Day. It was placed in suspended animation on 31 October 1945. ==Postwar==