Mussolini had spent his time as leader of Italy extolling the dynamism of Fascism and that Italy must embrace a destiny with war if it was to assume its position as a great power. "We will darken the sky with our aircraft!" and "A Million Bayonets will March!" were headlines written by Mussolini and backed by prewar propaganda that convinced everyone, at home and abroad, that Italy meant business and that its armed forces were at the cutting edge of effectiveness. However, the Italian industrial base could not meet the demands of total war. The armed forces owed their loyalty to the King and not Mussolini, and lacked the political fanaticism of Hitler's Germany or Imperial Japan.
When Italy joined the war on the back of Hitler's triumph it met defeat in all its endeavours. The British had been wary of Italian military capability but when their first counter attacks destroyed Mussolini's forces they feigned to despise the Italians and mocked them in their propaganda. And when Rommel was sent to bolster the Italian position in North Africa, Goebbels was quick to broadcast Axis triumphs as German, whilst Rommel always blamed his allies for all his setbacks. Thus, the Italians have suffered from a poor press ever since!
The Italian army was poorly equipped. Many design and production decisions were made for financial reasons and the economy struggled to meet Mussolini's ambitions, and so the army remained an infantry force, dependent on WW1 vintage artillery for support and lacking the armoured mechanisation that was vital for victory in the desert.
Italy began the war with under powered, under armed and under armoured tanks which just about held their own during 1941. By 1942, they were outclassed by the British and Fiat was struggling to build improved designs with the resources available. Nevertheless, the armoured formations, Ariete in particular, developed tactics and a battle plan that kept them in the campaign and ensured that they were an essential part of all Rommel's designs.
Alongside Ariete, the Italian's formed the Trieste Motorised Division which was the other fully mechanised formation that the Italians deployed. Well trained and led, it fought throughout the campaign.
Bersagliari, the Folgore Parachute Division and Engineer units were also well trained, and the Young Fascist units were highly motivated troops. However, the bulk of the infantry divisions, especially the colonial units, were poorly supplied and led, and without sufficient transport they struggled to survive in mobile desert fighting. Rommel often used these formations for besieging fortified positions or for maintaining the defence of essential areas but once the mobile Axis units were forced to retreat they were left to their fate without any choice but to surrender. At Alamein, Rommel alternated the units of Italian infantry with German formations as by this time he had lost faith in their ability to hold the line.
The artillery units, however, were renowned for their bravery and effectiveness. During Britain's first offensive, Operation Compass, the Italian gunners fought to the death. Their weapons were old fashioned, many of which were booty from the defeat of Austria Hungary in the last war. Yet, throughout the campaign, if dug in and with well established communications the Italian artillery was very effective, able to prepare fire plans that were more sophisticated than the Germans.
On balance, the Italian army was an essential auxiliary for Rommel. Without its contribution, including the weak infantry divisions, there would have been no Axis successes in the desert. However, on its own it is probable that the British would have secured victory in North Africa by early 1941!