My guess is that US Army would have followed French practice and towed the guns by truck on roads and used the tracked vehicles to tow the guns into position across
broken ground.
The 155mm gun wasn't quick into action since it required a hole to be dug below the breech to allow the gun to recoil fully at high elevation angles. Because of the
large traverse of the carriage it required something like 6 cu.m of soil to be dug out. I can imagine that frequent changes of firing position would be unpopular with the gun crews.
