Prior to the First World War, most artillery was still horse drawn, except for some heavy guns which were hauled by traction engines.  It was a French artillery officer, Lt. Col. DePort, who was responsible for the first practical four wheel drive motor tractor for guns.  In 1910, DePort first approached the firm of Panhard et Levassor with the idea for such a vehicle.  DePort himself worked for the ordinance firm of Chatillon Commentary, having retired from the Army in 1894.  At the time of the annual French Military Trials at Satory, in 1911, DePort showed his prototype for a Chatillon-Panhard, four wheel drive gun tractor to the official motor vehicle testing commission. 

It drove over the Satory cross country testing course with ease, taking slopes and small obstacles in it’s stride.  At the end of March 1912, the artillery testing commission asked DePort to give them a similar demonstration at Vincennes, this time towing guns.  The trials took place in July 1912, and the tractor was put through it’s paces towing 155mm field gun and limber and also towing a big 220mm siege mortar plus it’s baseplate, cradle and limber.  The tractor also carried a 14 man crew; in the case of the 220mm mortar the total drawbar weight was over 12 tons.

Over open rough ground the performance of the vehicle was excellent and it was decided to enter it in the 1913 Spring maneuvers where it would be tested with two other gun tractors, to which the Army was also testing.

One of these was two wheel drive vehicle and the other was a four wheel drive Latil. These vehicles were thoroughly tested in the trials with one non stop 100 km. Run unloaded and a non stop 60 km. Run towing guns plus numerous cross country and inter city runs with and without guns.

The transmission of the Chatillon-Panhard is so arranged as to involve no universal joints and only one differential gear.  This is mounted on a transverse countershaft, and the power is taken to the wheels through beveled gears at the ends of the countershaft, and four diagonal shafts driving in their turn auxiliary shafts upon which are bevels engaging with similar bevels on the wheels. 

At the end of the period 8-30 March, the tractors were stripped and examined.  All three vehicles proved satisfactory, but it was the Chatillon-Panhard which had put up the best performance and hauled the heaviest loads.  The artillery commission were most enthusiastic.  The French artillery had tried using a lorry to haul guns as early as 1907, but since only two-wheel drive vehicles had been available, movement was restricted to roads. 

Now here was a motor tractor which could pull heavy artillery over rough country.  Fifty Chatillon-Panhards were ordered at once- and delivered the following August-and a provisional order was given for another 50.  However, it was decided to hold further trials before confirming the second order.  This time six different vehicles were tried.  The previous years trials had been held in fine dry weather and it was felt that tests in really bad conditions were necessary to give a true idea of any vehicle’s capabilities.

In March 1914, the trials took place just as the thaw was setting in and heavy rain had turned the exercise ground into a quagmire.  This time non of the tractors performed particularly well, usually because the guns they were towing got bogged down and brought progress to a halt.  The wisdom of ordering so many tractors before all the problems of cross-country movement were overcome was therefore open to question and the second order for Chatillon-Panhards was cancelled.

It was decided that more “user” experience was necessary, and the first 50 vehicles were allocated to the 4^th Heavy Artillery Regiment for extended service.  This unit was equipped with 120-mm guns and was the first artillery in the French Army to be fully mechanized.  As such the regiment took pride of place in the Bastille Day parade in Paris on 14 July 1914.  When War was declared on 4 August, these 50 Chatillon-Panhards were the largest single group of vehicles in the French service.

The French Army at that time had only 220 motor vehicles altogether, including 91 assorted lorries, 31 assorted ambulances, and the balance made up of 2 “auto cannons” and a motley collection of staff cars and light service vehicles.  The Chatillon-Panhard tractors were swiftly at war and gave good service. The Chatillon-Panhard had a 40-hp motor (at least 1000 rpm) and a top speed of 17 km per hour.  Unloaded it could tow up to 15 tons but then its speed fell to 8 km per hour.  The turning circle had radius of approximately only 16ft.

References: 
The Arthur Constantin KREBS Web site by Philippe Krebs.
Military Transport of World War One by C. Ellis & D. Bishop, Blandford Press Ltd.
Motor Transports & War by Horace Wyatt, Hodder and Stoughton, 1914. 

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