(noun)

Definition: (Slang) Diddly-squat ——the least amount :  anything at all

Source: http://www.merriam-webster.com/dictionary/diddly-squat?show=0&t=1387336890

“They head down the mountain, back to base camp, and when they get there they don’t say diddly. They don’t talk. Not a word, like they get there they’re deaf and dumb.”

I understand that soldiers are scared, so they done something crazy and do not know how to explain it to the others, and ashamed to talk about that.