..... , one eyed walking & the lack of depth perception, however, caused his troops to fall off the side if they were ascending the pass, or if they were descending the pass while walking backwards.
Hence the British & Skippy expression "I fell over and hurt, or otherwise damaged, my khyber", which was a waste of perfectly good letters, when they could have just said "I fell on my bum".
While Slim's casualties were initially reduced by 50%, the rate went back up again when their sore bums meant that they had to stand and their heads stuck up above the parapet, where the ......