My Ole Man, Marine Sgt, said that in this time frame he practiced with equipment that allowed Marines to dig an instant fox hole. It was a post that you stabbed into the ground and ignited a fuse. A charge then forced a wedged shaped cone into the ground at 'marine' velocity resulting in a crater that allowed one to quickly dig "an instant fox hole" unto which you sought instant cover.
Must not have been too effective or perhaps too injurous. Never heard of the concept today.