So I had to drop out.

If you'll permit it, sir, I shall have to get back to camp the best way I can." "If you're that badly off I'll have an ambulance sent for you," Greg went on.

"But I don't understand your feet giving out so suddenly.

Take off one of your shoes and the sock." "That may not show much, but I'm suffering just the same, sir," rejoined the non-com in a grumbling tone.
"Let me see," Greg insisted.
While the sergeant was busy removing a legging and unlacing a shoe Captain Holmes glanced up the road to discover that the battalion was counter-marching.
"Be quick about it, Sergeant," Greg urged.
Moving no faster than he had to, Mock took off his shoe, then slowly turned the sock down, peeling it off.
"Is that the worst foot ?" Greg demanded, in astonishment.
"I don't know, sir; they both hurt me." "Do you want to show me the other foot, or do you wish to get back among the file closers ?" "I---I can't walk, sir." Down on one knee went Greg, carefully inspecting the foot and feeling it.

The skin was clean, rosy, firm.
"Why there isn't a sign of a blister," Captain Holmes declared.
"Nor is there an abrasion of any kind, or any callous.