Unternehmen Ochsenkopf (Operation Ox Head) also known as the Battle of Sidi Nsir and the Battle of Hunts Gap was an Axis offensive operation in Tunisia from 26 February to 4 March 1943, during the Tunisia Campaign of the Second World War. The offensive and a subsidiary operation Unternehmen Ausladung was intended to gain control of Medjez el Bab, Béja, El Aroussa, Djebel Abiod and a position known as Hunt's Gap, between the British First Army and the Axis Army Group Africa (Heeresgruppe Afrika/Gruppo d'Armate Africa). The offensive gained some ground, but none of the more ambitious objectives were achieved before the operation was called off due to increasing losses of infantry and tanks, particularly the heavy Tigers. Unternehmen Ochsenkopf was the last big Axis offensive by the 5th Panzer Army before the surrender of the Afrika Korps in May 1943.

After the Battle of Kasserine Pass (19–24 February), the Axis created Army Group Africa (Heeresgruppe Afrika/Gruppo d'Armate Africa) as a command headquarters for the 5th Panzer Army and the Italian 1st Army in Tunisia. Adolf Hitler and the German General Staff Oberkommando der Wehrmacht (OKW) believed that Generaloberst Hans-Jürgen von Arnim should assume command but Generalfeldmarschall Albert Kesselring the German Oberbefehlshaber Süd (OB Süd, Commander-in-Chief South) argued for Generalfeldmarschall Erwin Rommel, who was appointed to command the new Army Group Africa on 23 February. Comando Supremo, the Italian General Staff, ordered Rommel to end the attack at Kasserine, in view of the Allied reinforcement of the Tebessa area, to conduct a spoiling offensive against the Eighth Army (General Bernard Montgomery) as it approached the defences of the Mareth Line from the east.

The villages of Gafsa, Metlaoui and Tozeur were to be held by mobile troops and most of the attack group was to return to the 1st Italian Army. The 10th Panzer Division had retired from Thala by early on 23 February and the 21st Panzer Division ended its attack on Sbiba on 24 February. The divisions were to refit and also rejoin the 1st Italian Army, ready for an attack in early March, the moves to be covered by minor operations on the 5th Panzer Army front. On 24 February, Arnim flew to Rome without consulting Rommel and advocated an offensive towards Béja, being convinced that the British First Army (General Kenneth Anderson), had sent reinforcements south from the northern front to save Sbiba and Thala. Arnim gained the approval of Kesselring for an attack on a wide front against the V Corps (Charles Allfrey) sector on 26 February.

Unternehmen Ochsenkopf was a plan to penetrate the British defences on 26 February, with Korpsgruppe Weber (General Friedrich Weber) of the 334th Infantry Division, elements of the Luftwaffe Hermann Göring Division which had recently arrived and the parts of the 10th Panzer Division not involved in Unternehmen Frühlingswind (Operation Spring Storm), in three groups or horns, in the shape of a bull's head. The northern horn, with most of the tanks, was to advance on the route from Mateur from the north-east, to capture Béja 40 km (25 mi) west of Medjez.

The second group was to attack from Goubellat towards Sloughia and Oued Zarga to envelop the British at Mejez El Bab and the third group was to carry out a pincer attack in the Bou Arouda valley, then advance through El Aroussa to Gafour, with the objective of the road junction at El Aroussa. In the north, the improvised Division von Manteuffel (formerly Division von Broich), in the subsidiary Unternehmen Ausladung (Operation Disembarkation), was to defeat the British in the Sedjenane valley, cut the communications from Jefna to Djebel Aboid and cover the northern flank of Korpsgruppe Weber. The operations would force the allies to withdraw and delay a further advance, while Rommel prepared the attack of the 1st Italian Army (the former German–Italian Panzer Army) from the Mareth Line defences against the Eighth Army.

The subsidiary Unternehmung Ausladung began on the morning of 26 February, to outflank the British in Sedjenane and the high ground opposite Green Hill, with an attack on the hilly coastal strip to the north between the town and Cap Serrat. The area was lightly held by poorly equipped French troops of the Corps Francs d'Afrique. Division von Manteuffel led the attack with elite troops of the Luftwaffe Fallschirmjäger Regiment (motorized) "Barenthin" (Major Rudolf Witzig) and the Italian 10th Bersaglieri Regiment. The Axis forces, with air support from the Luftwaffe made good progress across the hills held by the Free French between Cap Serrat, the railway and Sedjenane. The French managed to repulse an Italian attack but were then overrun and many were taken prisoner.

On 27 February, elements of the 139th Infantry Brigade of the 46th Infantry Division and attached No. 1 Commando, supported by the 70th Field Regiment RA and 5th Medium Regiment RA, moved up to counter the German advance but lacked air support and were short of artillery, after taking part in the Battle of Kasserine. Until 1 March, the British conducted costly but successful counter-attacks, which delayed the Axis advance on the hamlet. On 2 March, a Durham Light Infantry (DLI) counter-attack was a costly failure and the battalion was withdrawn to a wooded area outside Sedjenane; more German attacks on Sedjenane that day and the next were defeated. A counter-attack by a battalion of the Lincolnshire Regiment, the DLI and Churchill tanks of the North Irish Horse drove the Germans back in determined fighting.

The British position became untenable due to withdrawals by the French further west in the Medjez area, when Axis troops occupied high ground dominating the town. The French commander had thought his position was being outflanked and ordered a withdrawal. The German penetration towards Béja and Medjez along with the French withdrawal had caught the 139th Infantry Brigade in a salient and two companies of Sherwood Foresters were overrun. On 4 March, the British retreated 24 km (15 mi) from Sedjenane toward Djebel Abiod to stabilise the front. The Axis attack on Djebel Abiod was delayed for five days by the defence of Sedjenane and it was not captured.