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 <WSD>marching</WSD> 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 narrowness of the road and their baggage and ammunition carts . 
Meaning of the word marked with <WSD> tags:  march in a procession