It seems that, when leaders are pressing hard to achieve their goals, people in the trenches will develop ways of ignoring all but the most direct of orders. And for good reason.

In the trenches in World War I, the Germans and the English were not continually fighting. Instead, they developed a complicated system of co-operation that meant neither side sustained heavy losses unless the Staff Officers had ordered a charge.
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This etiquette was finely honed over the course of the war. Both sides knew that if one side lost a man during dinnertime, then the other side would lose three when they were having their meal the next day. Similarly, flags on both sides marked places that that enemy snipers should consider out of bounds. This unlikely alliance was so deeply felt that apologies were made if it seemed to have been broken.

Insubordinate Survival Techniques