Transport of ammunition in ambulances?

"It was an awkward job getting the wounded down the narrow, crowded trench. I saw one poor devil, his breeches dark with blood, flung out of his stretcher and gasping in agony. One had to carry wounded men a long distance, a mile or more, for even when a road existed the ambulances never came very near the front line. If they came too near the Fascists had a habit of shelling them – justifiably, for in modern war no one scruples to use an ambulance for carrying ammunition."