Jubayl, Saudi Arabia. This fit included additional Chobham Armour along the hull sides and explosive reactive armour (ERA) on the nose and front glacis plate. Modifications also included the provision of extra external fuel drums and a smoke generator. There were major concerns about the reliability of the vehicle. Before the commencement of the Gulf War deployment only 22% of Challenger 1s were operational because of faults and lack of spares. In addition there were serious worries about how a tank designed to perform in temperate climates would stand the rigours of desert warfare. On 22 November 1990, it was decided to add the 4th Armoured Brigade to the force, under the umbrella of 1st (UK) Armoured Division. The new brigade had a single Challenger regiment, 14th/20th King's Hussars, equipped with 43 Challenger 1 tanks and reinforced by a squadron of the Life Guards. They were equipped with the Mark 2 version of the tank, which was upgraded by armouring the storage bins for the 120 mm charges as well as the additional armour fitted to the Mark 3. During Operation Desert Shield it was decided that the 1st (UK) Armoured Division would be placed under the command of the US VII Corps. This corps would form the armoured fist of the Coalition forces, tasked with destroying the bulk of the Iraqi forces. The forces of VII Corps crossed the Saudi border into Iraq, and then crossed into Kuwait. The 1st (UK) Armoured Division was the easternmost unit in VII Corps' sector, its Challenger tanks forming the spearhead of the advance. The division advanced nearly 350 km within 97 hours, destroying the Iraqi 46th Mechanised Brigade, 52nd Armoured Brigade and elements of at least three infantry divisions belonging to the Iraqi 7th Corps in a series of battles and engagements. They captured or destroyed about 300 Iraqi tanks and a very large number of armoured personnel carriers, trucks, reconnaissance vehicles, etc. Patrick Cordingley, the British commander of 7th Armoured Brigade, said later that "Challenger is a tank built for combat and not competitions.". The main threat to the Challenger was deemed to be the Iraqi Republican Guard's T-72M tanks; each British tank was provided with twelve L26A1 "Jericho" depleted uranium (DU) shells specifically for use against T-72Ms, but during the course of the Coalition's ground campaign none were encountered as the division was withdrawn beforehand. After the Gulf War, Challenger