Usually the best way to shorten how something is said is to eliminate words and combine to produce parallel construction.
That's what B has done. It has combined two equal nouns to form a compound subject. That cuts out quite a few words and it makes it sound like both Civilians and soldiers did the same thing (called Sam Wilson Uncle Sam). A is actually shorter by one word but and is not as well used. The began in B makes the sentence stronger. A compound subject is more to the point than a compound sentence.
Answer B