Staff Writer (Updated: 7/1/2014):
In 1940, the Italians began design work on a new 25-ton, "heavy" class infantry support tank intended to operate alongside the "M" family of medium tanks then in service. Recent fighting in the North African campaign showcased the drastic limitations of the Italian tanks then in service, prompting the Italian Army to entertain other options. The primary designation for this new tank was initially "P 75". The selected armament became a short-barreled 75mm 75/32 main gun and this was set within a traversing turret emplacement. The turret was affixed to a hull superstructure and the design was, more or less, of a highly conventional nature with long-running tracked sides - though decidedly Italian in general appearance. The originally selected engine became a diesel-fueled installation of 330 horsepower. The 75mm short-barreled gun was then upgraded to a more potent 75mm long-barrel 75/34 main gun.
After the diesel engine failed to impress, the Italian Army settled on a gasoline-fueled version, forcing Ansaldo engineers back to the development board which served to delay the program. This endeavor eventually produced a gasoline-fueled engine outputting at 420 horsepower. The new tank was now designated as the "P 40" and it was in this end form that the type survived prior to the Italian Armistice. From then on, the tank would be known under the formal designation of "P 26/40" - "26" marking the vehicle's weight in tonnes while "40" denoting its year of adoption into service.
Primary manufacture of the P 26/40 was conducted out of the Ansaldo facility in Northern Italy - even after the Italian Armistice. The vehicle maintained a running length of 19 feet with a width of 9 feet, 2 inches and a height of 8 feet, 2 inches. She was crewed by four personnel that included the driver, the tank commander, the ammunition handler and a radio-operator/machine gunner. Key to this arrangement was the commander for he also doubled as the gun layer which complicated in-the-field actions. Comparable tank systems from other nations incorporated a fifth crewmember to serve as a dedicated gunner while the commander could concentrate on communicating with his crew and observing (and reacting to) battlefield developments - where seconds could spell victory or total doom for the crew. Additionally, the P 26/40 was designed with only a two-man turret system which also limited internal space - three-man turrets were now proving the norm with all new tank designs appearing elsewhere. Not only was the workload of the commander doubled in the Italian design but creature comforts were few and far between. Couple the space required for each work station with the available ammunition stores, engine compartment and transmission "hump" running along the hull floor and one can imagine the rather tight confines of the Italian design. There was no commander's cupola to provide the vehicle commander with a perched position from which to observe actions from afar which proved another tactical limitation in-the-field.
Armor protection for the P 26/40 varied about her design, ranging from 14mm at her thinnest to 60mm at her thickest facings. While something of an improvement over preceding Italian tank designs, this was rather woeful when compared to the anti-tank weaponry being fielded by Italy's enemies. Any anti-tank gun larger than 40mm was said to be able to penetrate the base armor of the P 26/40 with relative ease at this point in the war. To compound issues in the Italian design, the armor was finished in riveted construction as opposed to the much more accepted welded construction appearing on tanks elsewhere. Not only was riveted construction weaker along the plate joints (regardless of actual plate thickness), the rivets themselves could fly about the fighting compartment in response to a direct hit from enemy fire - injuring or outright killing the crew within.