'MA3' was a British naval undertaking by Admiral Sir Andrew Cunningham’s Alexandria-based Mediterranean Fleet designed to provide escort and long-range support for the MF.1 fast and MS.1 slow convoys of empty ships from Malta to Egypt and also for the AS.1 convoy of likewise empty ships from Piraeus to Egypt (28 June/2 July 1940).

Under the command of Vice Admiral J. C. Tovey, second-in-command of the Mediterranean Fleet, the British force comprised the five modern light cruisers of the 7^th Cruiser Squadron in the form of Orion (flagship), Gloucester, Liverpool, Neptune and Australian Sydney as well as the older light cruisers Caledon and Capetown, and 16 destroyers. Air reconnaissance and support was provided by Short Sunderland flying boats operating from Alexandria and Malta.

At this same time, soon after Italy’s 10 June entry into the war, the Italian high command thought it probable that the British land forces in Egypt would advance to the west into Cyrenaica spearheaded by armoured forces, and decided to move an anti-tank unit to Tobruk as soon as possible. The Italian unit comprised 10 anti-tank guns, 110 tons of ammunition for these weapons, and 162 soldiers.

The Italian navy selected three 'Turbine' class destroyers to transport this anti-tank unit in the belief that success would be better guaranteed by these ships as they possessed the maximum speed of 36 kt and a good loading capacity. The three members of the class selected were Espero, Ostro and Zeffiro. The Italian flotilla was commanded by Capitano di Vascello Enrico Baroni. Two smaller escort vessels, Missori and Pilo dating from the period of World War I, were tasked to carry 52 troops and more supplies, and these departed independently for Tobruk some hours after the three more modern destroyers.

These Italians movements led, at a time before 'MA3' had fully started, to the so-called 'Battle of the Espero Convoy' on 28 June in an area to the south-west of Crete, where the British force was awaiting the arrival of the three convoys it was to shepherd to Alexandria.

Two Short Sunderland maritime reconnaissance flying boats sighted the Italian destroyers at about 12.00 some 50 miles (80 km) to the west of Zante island, the sighting report suggesting that the three Italian ships lay well within the attack range of the 7^th Cruiser Squadron, so Tovey ordered the cruisers (Force 'A') to intercept the Italian force on both flanks. At 18.30, the first 6-in (152-mm) salvoes from the five British cruisers began to fall on the surprised Italian convoy at a range of 17,500 yards (16000 m). Appreciating the fact that his ships were completely outgunned, Baroni attempted to cover his destroyers with smokescreens and to evade the attentions of the British with speed and manoeuvre. Unable to escape achieve this object, Baroni opted to sacrifice his ship, Espero, to save the others. While Baroni remained behind in his ship to fight an unequal battle, Ostro and Zeffiro headed to the south-west at full speed.

It was not until 19.20 that the first British broadside struck home, when the range had closed to 14,000 yards (12800 m), and by this time Tovey had given up the chase of the other two destroyers. The ships of the 7^th Cruiser Squadron expended some 5,000 rounds before Espero succumbed after 130 minutes of fierce fighting. A single Italian 120-mm (4.72-in) shell hit Liverpool, but caused little damage.

The battle resulted in such a shortage of ammunition that the planned MF.1 fast and MS.1 slow Malta convoys were suspended for two weeks, when their movement was supported by 'MA5'.

Sydney rescued 47 men from the Italian destroyer, and six others were later found alive by an Italian submarine almost 20 days later. Ostro and Zeffiro reached Benghazi on the following day and arrived at Tobruk shortly after that.

Each side learned an important lesson from this small engagement. The British now appreciated that a daylight naval action at long range was unlikely to be decisive when the Italian units had greater speed. The Italians now understood more perfectly the all-important nature of well co-ordinated aerial reconnaissance, for had Italian aircraft spotted the Allied cruisers before they reached the position to open fire, all three of the destroyers would have escaped unscathed.

On 29 June British aircraft sighted and reported Italian submarines, and in the follow-up to this report the submarines Argonauta, Uebi Scebeli and Console Generale Liuzza were sunk by carrierborne aircraft and the surface attacks of the Force 'C' destroyers Dainty, Decoy, Defender, Ilex and Australian Voyager.

The British ships returned to Alexandria on 2 July.