Holt Caterpillar 5 Ton Prototype SPG Schneider Howitzer Original Photograph RARE

Description

The tracks look to be earlier than the Mark I but still very similar.  The platform is different as this one does not have one, just what looks like a Schneider howitzer mounted on it.  Which makes me think this might be some kind of prototype (notice the covers) and also makes this possibly photos are at one of their manufacturing plants.
I have many other photos in this set where it appears that the machines are going through some testing so this is quite possibly some of the earliest photos at one of the most iconic companies in the world.
"In 1918 Pliny E. Holt, the chief designer of the Holt AA vehicle joined the design staff of the Rock Island Arsenal, Illinois. Design and construction under Holt's supervision commenced to build tracked vehicles carrying the 8 inch howitzer, 155mm GPF and 240mm Schneider howitzer known as Marks I to III respectively. These vehicles were based on components of the Holt artillery tractors and proved to be very heavy and also slow. It should be noted that the American concept was of a gun carried by a minimal tracked vehicle rather than a self-contained weapon system carrying gun crew, ammunition as well as the gun which was the British and French approach to SPGs.
The Rock Island Arsenal produced an SPG based on the French St Chamond SPG6, the Mark IV, with a petrol-electric powered tractor with a tethered electrically powered gun vehicle.
The Ordnance Dept testing showed that although the Marks I to III SPGs had some promise future designs would have to be much lighter and smaller. The War Munitions Board saw the logic of SPGs to improve the battlefield mobility of the artillery and to reduce the costs associated with horse transport. Production contracts for 50 Mark I, 50 Mark II and 250 Mark III and Mark IV/IVA self-propelled guns were let in 1918 with delivery expected in early 1919. The Armistice in Nov 1918 lead to the reduction of the production contracts to a few experimental vehicles.
The Ordnance Dept in 1918 constructed a pair of light SPGs based on the Holt 2½ and 5-ton artillery tractors carrying the 75mm M1916 gun. Although these SPGs were improvised they demonstrated the viability of SPGs carrying light field guns."
I believe these may actually be a picture some 5 ton prototypes mentioned above with the larger guns that proved to be too slow, based on the fact that the tracks appear to be very similar to the 5 ton tracks, but the guns are way too big for the 75mm M1916 size.  I actually think the guns are the 240mm Schneider howitzers.
A very rare photo.
Measures approximately 4 1/2 by 2 3/4
Box J 08192021
Weight  0 ounces