Some sense of the challenges of driving a six-horse team with a heavy gun and limber behind can be acquired by reading Field Artillery Training.
Driving uphill requires every horse to lean its weight into its collar:
“By assuming a lower and more advanced carriage of the head and neck than he would do if moving balanced and out of draught, he is able to add considerably to his power. He should therefore be allowed full liberty of rein when ascending a steep hill.”
The Manual also tells us something that is not intuitive: “A draught horse can put more weight into his collar if ridden. Gunners should, therefore, be mounted on the off lead and centre horses when circumstances demand it. All men riding draught horses up hill should lean forward.”
And if necessary, the gunners, already walking to lighten the load, are to hook drag ropes onto the vehicle and lend their own strength to the venture.
Driving downhill puts most of the responsibility on the wheel horses and drivers, while the lead and centre horses ease up without dropping the traces:
“The wheel driver with his right hand on the leading rein keeps his horses steadily in the breeching, taking care not to throw them on their haunches.” It is not entirely up to the wheel horses to restrain the momentum, fortunately, since the vehicles do have a brake, and if it is very steep, the men can haul back on drag ropes to slow the descent.
The image is one of the works of an American war artist, George Harding. It is called “Pulling a caisson uphill.” A caisson is an ammunition wagon, two-wheeled, usually attached to a limber to make a more stable four-wheeled vehicle. Why there is what appears to be a second wagon piled on top of the caisson I cannot tell, but there is no doubt about the effort demanded of both animals and men.The image is found in the on-line version of the second volume, entitled The United States Army in a Global Era 1917-2003, of American Military History, published by the US Army’s Centre of Military History . (Washington, 2005. 39)