The short version is that the Italian Army after the armistice was never an entity able to operate on a scale or with a scope comparable to the Army before the armistice. The Italian Co-belligerent Army (Allied side) numbered at most five to six “short” division on active front, for a total of less than 30000 men. The Italian Republican Army (Nazi side) was mostly employed in anti-partisan and police duties and reached barely 60000 men in four regular divisions. The entirety of the partisan forces (Allied side) in Italy reached a peak of around 230000 at the end of the German occupation and therefore outnumbered the previous two; but not all of them were organized in military formations proper. The question of which one of these was the “true” Italian Army is quite loaded and I don't think it belongs on the short version.

As a matter of fact though, with the armistice the Italian Army as an independent entity, with its own strategy and goals and doctrine and all those things that are used in comparing the effectiveness of two armies ceased de facto to exist.

Even with its shortcomings, the Italian Army had fielded over 3000000 men – you will forgive me here but the most bizarre and uneven numbers are given on different sources and this has never been my prime interest, so if some numbers seem off I might be wrong; I'm trying to keep it to active personnel more or less – involved in extremely complex operations, if poorly planned, such as an aborted dual invasion of Egypt; police and occupation of large regions of the Balkans (that saw alone over 300000 soldiers employed) and to a lesser degree France; the expedition of an entire Army to the Russian front numbering 250000 men.

Nothing of the sort was even conceivable for any of the post armistice forces.

 

Now, if you want to know something more, I go a bit into details in the following – and it is quite confusing since the overall situation was quite confusing.

By July 23^rd 1943, Italy's ability to perform large scale military operations was essentially destroyed. The failure of the war in North-Africa, the disaster of the Italian Army in Russia, the growing disillusionment of the population with the regime – with major strikes resurfacing in northern industrial centers, despite the conditions of the workers being comparatively better than those of other belligerent nations – the fact that the establishment, King included, were no longer looking at a military defeat as the worst possible scenario; all made it impossible for Italy to continue the war. The Allied landing in Sicily with the Army unable to put up a significant resistance confirmed this fact.

Taking all these into account, and finally persuaded by the Grand Council resolution of the 23^rd that Mussolini had lost support even among his own men, the King dismissed him from his position of Presidente del Consiglio and replaced him with Marshal Pietro Badoglio – whose government was to last until April 17^th. It was a military government to mark its loyalty to the King and its discontinuity with the Fascist Regime; and in fact there was a short supply of political figures both non military and non fascist in the country, so that the choice was somewhat obligated.

Given the nature of the Fascist Regime, this lead change did not have immediate significant effects on ordinary administration. More so the new Prime Minister, together with the King, reassured the German ally that Italy was to continue the war. Most of the Country though, understood that the Italian war effort had come to an end – a fact that was often welcomed with spontaneous manifestations of enthusiasm. Those reassurances did not fool the Germans who immediately took preventive steps to take control of the former ally in case of armistice (operation Achse).

Meanwhile the Italian Government was in fact in the process of signing an armistice; a process that was not as easy as imagined. First, not everybody was on board with the idea of unconditional surrender, which would have let Italy at disposal of the Allies for what could have been a significant period of time, during an ongoing conflict; second, the Italian surrender was a possible source of political friction between the Allies – we'll get back to that later; third, there was the issue of preventing the German occupation and therefore committing a relevant number of men to an uncertain endeavor under short notice.

The negotiations, mostly in Lisbon, a place where both Italy and the UK had diplomatic relations, took therefore over a month.

During this month the Italian Army was not in a state to do much, nor there was any reason to engage in offensive actions – at least major offensive actions – on either side.