'Red Vault' was a US operation by Lieutenant General George S. Patton’s II Corps of Lieutenant General K. A. N. Anderson’s Allied 1^st Army against the Axis forces in the southern part of central Tunisia (23 March/3 April 1943).

This Battle of El Guettar pitted elements of Generaloberst Hans-Jürgen von Arnim’s Heeresgruppe 'Afrika' against the II Corps, and is notable as the first battle in which US forces defeated combat-experienced German armoured units.

The II Corps had been severely handled in its first encounter with the German and Italian forces in Tunisia in a series of battles which culminated in the disastrous Battle of the Kasserine Pass, the 'Sturmflut' last phase of the German 'Morgenluft' undertaking at a time late in February 1943. Although then on the verge of a major tactical success, Generalfeldmarschall Erwin Rommel had halted the battle and returned his attention to the Axis forces' eastward-facing defences at the Mareth Line on learning of the approach of Lieutenant General Sir Bernard Montgomery’s British 8^th Army. Thus the Battle of the Kasserine Pass ended with the US forces still in the field: the II Corps had lost lost ground, men, matériel, and much of its confidence in a number of senior commanders.

The US command had responded rapidly to the failure of their forces with a series of major command, discipline and tactical changes. One of the major changes was the introduction of greater flexibility in artillery communications, allowing all batteries within range of a target to respond to a single call for fire: up to this time each battery could fire only on the direct command of its dedicated observers, spread out over the lines and using different frequencies to communicate with their batteries. Another significant modification was that large units were kept massed rather than being broken up into smaller, unsupported elements as had been done under the leadership of Major General Lloyd C. Fredendall. A start was also made on the improvement of co-ordination with air support elements, but this did not reach truly satisfactory levels until a later time.

On 6 March Patton succeeded Fredendall in command of the II Corps, and his first objective was the reorganisation of this formation for an offensive back toward the Dorsale Orientale chain of the Atlas mountain range. If successful, this would threaten the right rear of the Axis forces defending the Mareth Line facing Montgomery’s 8^th Army and ultimately make their position untenable.

On 17 March Major General Norman D. Cota’s 1^st Division moved forward into the almost abandoned plains, taking the town of Gafsa, which was quickly organised as a forward base for further operations. On 18 March Lieutenant Colonel William O. Darby’s 1^st Ranger Battalion pushed forward to occupy the oasis of El Guettar, again only very limited opposition as its Italian defenders fell back and took up position in the hills overlooking the town, thereby closing the El Guettar mountain pass which provided the primary exit from the interior plains to the coastal plain. Another operation took one of the Italian positions and 700 prisoners on the night of 20 March after the Rangers had scaled a sheer cliff and passed ammunition and equipment up hand-over-hand. The US forces were now excellently situated for an offensive.

The Axis commanders had become aware of the US movements and decided that Generalleutnant Friedrich Freiherr von Broich’s 10^th Panzerdivision should drive them back. Rommel had flown to Germany before the battle, leaving von Arnim in control of the newly named Heeresgruppe 'Afrika'. Like Rommel, von Arnim had a decidedly low opinion of the US forces' combat capabilities, and felt that a show of force would be enough to clear the Americans out of the Dorsale Orientale.

At 06.00 on 23 March, 50 tanks of the 10^th Panzerdivision emerged from the pass into the El Guettar valley, the tanks being followed by Marder tank destroyers and Panzergrenadier troops, and the Germans quickly overran the US first-line infantry and artillery positions. Cota himself was threatened when two tanks came near his headquarters, but rejected all suggestions that he should move himself and his headquarters. The German endeavour began to falter as its leading waves entered a minefield, however, and as the German armour slowed, US artillery and anti-tank guns opened fire on it: among the US weapons were 31 M10 tank destroyers, powerful equipments which had arrived only in the last few days. In the next hour, 30 of the 10^th Panzerdivision's tanks were knocked out, and by 09.00 the survivors had retreated from the valley.

The Germans made a second attempt from 16.45, after waiting for their infantry to form up. Once again the US artillery was able to disorganise the attack in a major fashion, eventually breaking the charge and inflicting heavy losses. Realising that further attack would not yield a useful result, the rest of the 10^th Panzerdivision dug in on the hills to the east or retreated back to the German headquarters at Gabès.

On 19 March the 8^th Army launched its 'Pugilist-Gallop' attack on the Mareth Line, at first with little success. However, on 26 March, a force sent via an outflanking inland route arrived in the area to the north of the Mareth Line, so rendering the Axis defences no longer tenable. A full retreat started to a new line set up at Wadi Akarit, to the north of Gabès, and this made the US position still more important as the road through El Guettar led directly into Gabès. During the following week, the US forces slowly moved forward to take the rest of the interior plains and establish lines across the entire Dorsale Orientale.

The German defences were formidable, and as a result the US advance was both slow and costly. On 23 March, the 10^th Panzerdivision fell on Lieutenant Colonel Robert H. York’s 1/18^th Infantry of the 1^st Division, and the German armour broke through the valley between the 1/18^th Infantry and 3/18^th Infantry, reaching a position about 6 miles (10 km) behind the 1/18^th Infantry. In this action, German tanks and self-propelled guns, together with infantry in half-track carriers and trucks, overran the 32^nd Field Artillery Battalion and part of the 5^th Field Artillery Battalion, and the Italian command reported that 40 tanks had been destroyed and 170 Allied troops had been captured.

By 30 March, however, the formations of the II Corps were in position for an offensive to the south from El Guettar. In order to make the start of a break-out feasible, the two original Italian strongpoints on Hill 369 and Hill 772 had to be taken, one after the other. Patton’s plan involved the 1^st Division, Major General Manton S. Eddy’s 9^th Division and one combat command (1/3^rd) of Major General Orlando Ward’s 1^st Armored Division, grouped as 'Benson' Force. This attacked Hill 369 on the afternoon of 30 March but ran into mines and anti-tank fire, losing five tanks. The tanks were removed, and the 1^st and 9^th Divisions attacked again at 06.00 on the following day, moving up and taking several hundred prisoners. However an Italian counterattack drove them back from their newly gained positions, and by 12.45 the US forces were back where they had started with the loss of nine tanks and two tank destroyers. Another attempt on the following day also failed.

At this point Patton received orders to start the attempt on Hill 772, even though Hill 369 was still under Italian control. The 9^th Division was moved toward Hill 772, leaving the 1^st Division on Hill 369. By 3 April, the 1^st Division had finally cleared Hill 369, but the battle on Hill 772 continued. The commander of the Axis 1^st Army, Generale d’Armata Giovanni Messe, then called for support from Generalleutnant Hans-Georg Hildebrandt’s 21^st Panzerdivision, further slowing the US advance. The tempo of operations slowed and the line became largely static.

On 6 April the 8^th Army once again overran the German lines, and this triggered a full Axis retreat to the north. On the morning of 7 April, 'Benson' Force moved through the positions held by the 1^st and 9^th Divisions, and raced down the abandoned road linking El Guettar and Gabès, where it met the leading elements of the 8^th Army at 17.00.

The II Corps had lost 22 tanks and between 4,000 and 5,000 men killed or wounded, while the Axis forces had lost 37 tanks and between 4,000 and 6,000 men killed or wounded.

The results of the Battle of El Guettar were still decidedly mixed: the US formations and units had showed they could fight successfully in a defensive operation during the opening stages, but they had also demonstrated a lack of power when moving into offensive operations of their own. What could not be denied, however, was that the US performance in the Battle of El Guettar was very significantly better than that which had been revealed in the Battle of the Kasserine Pass.