Both units were equipped with semi-mobile 3-inch guns of 1918 pattern[a] and were deployed to defend the initial five airfields round Reims from which Bristol Blenheims of the AASF began reconnoitring and raiding over Germany.

[8][9] The first intimation that the Phoney War was about to end came in late April when a lone Junkers Ju 88 bombed a hospital next to Reims Cathedral; it was engaged by British and French AA guns but escaped.

However, the AASF flew many missions and took heavy casualties against the Ardennes breakthrough, while its airfields were subjected to dive-bombing and low-level attacks with which the old 3-inch guns and their Vickers Predictor No 1 and height-finders could not cope.

12 AA Brigade set off towards Nantes, its regiments 'trundling their old 3-inch guns at their maximum speed of 10 to 12 mph, though Vendôme, Le Mans and Rennes on the long haul westwards'.

Together with a Troop of 162/54 LAA Bty, 157 and 159 Btys moved 630 miles (1,010 km) to Marseille where they joined 'Haddock Force', manning airfields to launch bombing raids by RAF Wellingtons against Italian targets.

However, the surrender of France meant that Haddock Force was evacuated from Marseille to Gibraltar aboard a merchant ship with the remaining Bofors guns mounted on its decks.

At Tadcaster the brigade was under Northern Command, which gave it responsibility for some anti-invasion defence measures in Lincolnshire between the Humber and the Wash.[2] In October 1940 12 AA Bde HQ was ordered to proceed to Paignton and re-mobilise for overseas service.

In September 1941 the WDF made a small advance to Halfaya Pass and 12 AA Bde moved up to Sidi Barrani to protect nearby landing grounds (LGs), with 2nd LAA Rgt coming under its command.

General Erwin Rommel's counter-attack caused confusion, with retreating units driving through the LGs and both Eighth Army and 12 AA Bde's HQs.

Slater, BAA of Eighth Army, organised a temporary mobile column of LAA guns and light trucks (known as 'Slatforce') to operate behind enemy lines and cause disruption.

Reaching Msus that evening, the brigade found the enemy already approaching, so the retreat continued: 12 AA Bde had to abandon the forward LGs and Benghazi, moving back through Gambut to the airfield at El Adem, which was one of the fortified 'boxes' in Eighth Army's Gazala Line.

The 11-day battle to break through the Axis lines opened on 23 October, and after the break-out the airfields at Gambut and El Adem were quickly secured, 12 AA Bde's units following close behind.

The brigade developed an efficient system of providing rolling support for the DAF's tactical wings as they made long shifts forwards to maintain contact with the advancing army.

They selected new sites for landing strips or renovated old ones, maintaining radio contact through RAF or RA channels with the main body so that movement orders could be passed to the following AA batteries.

Movement was usually by 'leap frogging' from previously occupied LGs, though sometimes an AA battery was waiting in a hidden concentration area ready to move forward.

12 AA Brigade had 20–30 separate convoys moving on any given day, and by November it was providing cover for six RAF wings and one US Army Air Force (USAAF) Group, and also manning dummy airstrips, compete with flare-paths, aircraft, flash simulators and people.

For the Battle of the Mareth Line in late March 1943 12 AA Bde covered nine forward LGs for five RAF wings, all within 20 miles (32 km) of enemy positions.

[39] 57th HAA Regiment was to land after the beach groups to secure the immediate objectives along with the infantry divisions' LAA:[40] The first major hitch occurred when Montecorvino Airfield was not captured in the first rush, and continued to be fought over for the next four days.

Part of the brigade drove through the traffic-clogged Maiori Pass, suffering casualties from mortar fire, while the remainder re-embarked on LSTs for the short voyage to Castellammare di Stabia.

[2][40] When Wheeler left on 6 November for an important archaeological posting in India, Lt-Col Gerald Eastwood was promoted from 14th LAA Rgt to command 12 AA Bde.

12 AA Brigade then had a comparatively stable period of deployment until the end of the year, based on Capua, Cancello and Grazzanise, its batteries frequently engaging corps' targets in the forward area with ground fire.

[2] The renewed attack on Cassino began on the night of 11/12 May, with HAA guns supplementing the artillery barrage (one regiment fired 23,000 rounds in a week), particularly for counter-mortar shoots.

The brigade's LAA regiments were committed to bridges, defiles, assembly areas and artillery positions, and enemy aircraft were active in low-level strafing and bombing.

XIII Corps, on the other hand, after crossing the Rapido river, advanced along Highway 6 up the Liri Valley (Operation Diadem) on a narrow front, with continual demands for HAA guns in the medium artillery role.

[2][48][51] After the capture of Rome, 12 AA Bde provided one HAA battery to each divisional artillery in X Corps, the remainder guarding airfields and river crossings in the Tiber Valley, with the following organisation.

However, Luftwaffe activity declined towards the end of the year, and the Allied forces in Italy were suffering an acute manpower shortage, so surplus AA gunners were transferred to other roles (97th HAA and 99th LAA Rgts became infantry) and several units disbanded.

Its remaining units were spread thinly to defend a large number of roads, ports and railheads for Eighth Army and landing grounds for the DAF.

Eighth Army began its Spring offensive Operation Grapeshot on 6 April with carpet bombing by aircraft guided by a line of HAA bursts at 15,000 feet (4,600 m) fired by 12 AA Bde's guns.

Because of a general shortage of ammunition, the 40 mm Bofors guns were tried in ground roles, proving useful in hitting pinpoint targets such as enemy OPs, sniper or mortar positions, and buildings.

[2][48][55] As Eighth Army advanced rapidly through northern Italy, 12 AA Brigade moved up to Ferrara where it was ordered to stand down on 1 May; hostilities on the Italian front ended with the Surrender of Caserta the following day.