Conceived by the commander-in-chief of the British Middle East Command, General Archibald Wavell, Brevity was intended to be a rapid blow against weak Axis front-line forces in the Sollum–Capuzzo–Bardia area of the border between Egypt and Libya.

While Allied divisions were being diverted from North Africa, the Italians reinforced their positions and were supported by the arrival of the German Afrika Korps under Generalleutnant Erwin Rommel.

Rapidly taking the offensive against his distracted and over-stretched opponent, by April 1941 Rommel had driven the British and Commonwealth forces in Cyrenaica back across the Egyptian border.

Although the battlefront now lay in the border area, the port city of Tobruk—100 mi (160 km) inside Libya—had resisted the Axis advance, and its substantial Australian and British garrison constituted a significant threat to Rommel's lengthy supply chain.

Wavell defined Operation Brevity's main objectives as the acquisition of territory from which to launch a further planned offensive toward Tobruk, and the depletion of German and Italian forces in the region.

With limited battle-ready units to draw on in the wake of Rommel's recent successes, on 15 May Brigadier William Gott attacked in three columns with a mixed infantry and armoured force.

Renamed XIII Corps and reorganised under HQ Cyrenaica Command (CYRCOM), the troops of the former Western Desert Force adopted a defensive posture.

Commanded by Generalleutnant Erwin Rommel and consisting of the 5th Light and 15th Panzer Division, the Afrika Korps was to block British attempts to drive the Italians out of the region.

The 9th Australian Infantry Division fell back to the fortress port of Tobruk and the remaining British forces withdrew a further 100 mi (160 km) east to Sollum on the Egypt–Libya border.

[11][12] With the main Axis force conducting the siege of Tobruk a small battlegroup (Kampfgruppe) commanded by Colonel Maximilian von Herff continued to press eastwards.

Operation Brevity's primary objectives were to recapture the Halfaya Pass, to drive the enemy from the Sollum and Capuzzo areas, and to deplete Rommel's forces.

[13] On the desert flank to the south, the 7th Armoured Brigade group was to move 30 mi (48 km) from Bir el Khireigat to Sidi Azeiz destroying any opposition encountered en route.

[24] In the centre, the 22nd Guards Brigade group was to clear the top of the Halfaya Pass, secure Bir Wair, Musaid, and Fort Capuzzo, and conduct a company-sized probe toward Bardia.

The Afrika Korps war diary noted that "In the past, such reports had always been issued prior to the important enemy offensives to capture Sidi Barrani, Bardi, Tobruk, and the Gebel".

[23] Rommel strengthened the eastern side of his cordon around Tobruk as a precaution against sorties from the garrison and to order Kampfgruppe von Herff to adopt a more aggressive posture.

[13][25][28] Reaching the top of the Halfaya Pass, the 22nd Guards Brigade group ran into heavy opposition from a company of the 8th Bersaglieri Regiment, supported by anti-tank guns, under the command of Colonel Ugo Montemurro.

[33][34] In the afternoon, one company of the 2nd Scots Guards probed toward Bardia, the infantry coming under heavy machine gun fire from three positions as they neared Sollum barracks.

By midday, the brigade group had reached a position west of Fort Capuzzo, and in the afternoon the nine remaining cruisers of A Squadron 2nd RTR began a reconnaissance patrol towards Sidi Azeiz.

[37][38] Although the German and Italian commands in North Africa knew that a British offensive was imminent, Operation Brevity nevertheless caught them unprepared, and Rommel recorded in his diary that the initial attacks had caused him considerable losses.

Forces around Tobruk were redeployed east of the besieged city, to block any attempt at relief and to prevent the garrison from breaking out to meet the British advance.

A fortuitous dust cloud aided their withdrawal but by 14:45 Panzer Regiment 5 was reporting that it had recaptured Capuzzo, inflicting heavy casualties on the British and taking 70 prisoners.

A Squadron's patrol was interpreted as an attempt to concentrate south of Sidi Azeiz, in preparation for a thrust north the next day; such a move threatened to sweep aside Herff's force and unhinge the German front in the Sollum–Bardia area.

[37][39][45] Realising that the 22nd Guards Brigade group would be vulnerable to German armoured counterattacks in the open ground around Bir Wair and Mussaid, Brigadier Gott withdrew it during the early hours of the morning of 16 May.

[54] Lieutenant Giacinto Cova, a platoon commander in the 8th Bersaglieri Regiment, received a posthumous Gold Medal of Military Valour, Italy's highest award for bravery.

[55] The British received plaudits from Winston Churchill, who sent a telegram to Wavell betraying his ignorance of events by stating: "Without using the Tiger cubs you have taken the offensive, advanced 30 mi (48 km), captured Halfaya and Sollum, taken 500 German prisoners and inflicted heavy losses in men and tanks.

[46] The Tiger convoy brought 238 tanks and made it possible to refit the 7th Armoured Division, which had been out of action since February as a result of the losses it sustained during Operation Compass.

[51] Operation Brevity highlighted to Rommel the importance of the Halfaya Pass; whichever side held it would have a "comparatively safe route for his supplies" during offensives in the area.