The Italian 10th Army (10ª Armata) had been destroyed by the British, Commonwealth, Empire and Allied Western Desert Force attacks during Operation Compass (9 December 1940 – 9 February 1941).

The brigade failed to prevent Axis flanking moves in the desert south of the Cyrenaican bulge, which left Australian infantry in Benghazi no option but to retreat up the Via Balbia.

Sonnenblume succeeded because the ability of the Germans to mount an offensive was underestimated by General Archibald Wavell, the Commander in Chief Middle East, the War Office and Winston Churchill.

After numerous delays, the scope of the offensive was reduced to an advance by the 10th Army (Marshal Rodolfo Graziani) into Egypt, as far as Sidi Barrani and attacks on any British forces in the area.

On 16 September, the 10th Army halted and took up defensive positions around the port of Sidi Barrani, intending to build fortified camps, while waiting for engineers to extend the Litoranea Balbo (Via Balbia) with the Via della Vittoria.

The 10th Army was swiftly defeated, Sidi Barrani and Sollum were re-captured, and the British continued the operation, attacking through Cyrenaica to capture Bardia, Tobruk, and Derna.

Combe Force, an ad hoc flying column, moved through the desert south of the Jebel and intercepted the last organised units of the 10th Army at the Battle of Beda Fomm.

[5][6] The war was fought primarily in the Western Desert, which was about 240 mi (390 km) wide, from Mersa Matruh in Egypt to Gazala on the Libyan coast, along Via Balbia, the only paved road.

[9] The Sirocco (also known as Gibleh or Ghibli), a hot desert wind, blows clouds of fine sand which reduces visibility to a few yards and coats eyes, lungs, machinery, food and equipment.

[12] After the Italian defeat in Operation Compass, Tripoli was the last remaining Axis port, with a maximum unloading capacity of four troopships or five cargo ships at once, enough for the delivery of about 45,000 long tons (46,000 t) of freight per month.

Luftwaffe air units arrived in Italy in October, to carry Italian troops to Albania and then on 15 November, Luftflotte 2 (Generalfeldmarschall Albert Kesselring) transferred from Germany and Fliegerkorps X (General der Flieger Hans Geisler) moved from Norway to Sicily.

Attacks were to be made on British supply routes to Egypt and Axis forces in North Africa were to be supported by the Fliegerführer Afrika (General Stefan Fröhlich).

Rommel had been ordered in January by the Commander in Chief of the German army, Generalfeldmarschall Walther von Brauchitsch, to defend Tripoli and Tripolitania, albeit using aggressive tactics.

[30] Attempts by the British to re-open Benghazi were frustrated by lack of transport, poor weather and the Luftwaffe which began bombing and mining of the harbour in early February.

Neame was ordered to conserve the tank units as far as possible, yet inflict losses on the Axis forces if they attacked, fight a delaying action as far as Benghazi if pressed and abandon the port if necessary.

There was no prospect of reinforcement before May so the high ground of the escarpment nearby and the defiles to the north near Er Regima and Barce in the Jebel Akhdar, were to be held for as long as possible.

The 3rd Indian Motor Brigade (Brigadier Edward Vaughan) arrived at Martuba in late March with its transport but no tanks, artillery, anti-tank guns and only half its wireless sets, to be ready to move towards Derna, Barce or Mechili if the Axis attacked.

Air reconnaissance on 3 April, revealed that the British were still retiring and Rommel ordered a probe around the southern flank by an Italian detachment and several German platoons were sent under Lieutenant-Colonel Gerhard von Schwerin towards Maaten el Grara, from where they were to observe the ground towards Msus, south-east of Benghazi and Ben Gania further south.

[35] On 3 April, Gambier-Parry had received a report that a large enemy armoured force was advancing on Msus (now Zawiyat Masus in the Fati Municipality), site of the main divisional supply dump.

On 6 April, British air reconnaissance reported that there were Axis columns in the desert and the 3rd Indian Motor Brigade repulsed an attack at Mechili, which led to O'Connor at the CYRCOM headquarters (Neame had left to visit Gambier-Parry), to order a general withdrawal.

Rimington decided that the armoured brigade lacked the fuel to reach Mechili and ordered a move to Maraura, where a small amount of petrol was found.

General Streich, the 5th Light Afrika Division commander, was ordered on to Tobruk with Machine-Gun Battalion 8, part of Panzer Regiment 5 and an anti-tank company.

On 6 April, the Ariete Division reached Mechili and at noon, Ponath re-assembled his group near Derna airfield and cut one of the British withdrawal routes.

During the withdrawal, Neame, O'Connor and Brigadier Combe had left Maraua at 8:00 p.m. and taken a desert track at Giovanni Berta but then took a wrong turning north towards Derna, instead of east to Tmimi and ran into Group Ponath near Martuba.

[42] Rommel hoped to pursue CYRCOM across Egypt and take Alexandria but overstretched supply lines, opposition from OKW and the British defence of Tobruk made this impossible.

Many strafing attacks were made on parties of British troops and vehicles but these were not concentrated on bottlenecks, despite the few routes of retreat round the Cyrenaican bulge and south of the Jebel Akhdar.

The fighter squadrons had to resort to wasteful standing patrols over important areas and were able occasionally to give cover to traffic jams but were unable to prevent air attacks on two petrol convoys, which were destroyed.

Comando Supremo (Italian armed forces high command) wanted a pause before advancing into Egypt, as did Hitler, who also considered the capture of Tobruk to be essential; Rommel demanded more aircraft to carry ammunition, fuel and water forward.

Another attempt was made later and by dawn a small bridgehead had been established; Panzer Regiment 5 drove through and turned northwards, ready to divide into one column for the harbour and one to move west and cut off the garrison but the advance was stopped.

[55] Operation Brevity (15–16 May), was a limited British offensive, planned as a rapid blow against the weak Axis front-line forces around Sollum, Fort Capuzzo and Bardia on the Egyptian–Libyan frontier.