Sentence:  Someone said that while we were standing here and arguing about it , the British would be gone ; but Cousin Simmons said he had watched them marching west early in the morning , and moving at a much brisker pace it had still taken half an hour for their column to pass , what with the <WSD>narrowness</WSD> of the road and their baggage and ammunition carts . 
Meaning of the word marked with <WSD> tags:  the property of being narrow; having little width