What does the following sentence mean? Especially the part in the parentheses.
One of the keys of Sharpe's popularity is that he is always (in the thick of the action) shooting and slashing along with the rankers. .
Thanks in advance
"one of the keys to" = "one of the explanations for"
"in the thick of the action" = "where the action is fiercest and busiest"
"shooting and slashing" = "firing guns and wielding swords"
"with the rankers" = "with the common infantry"
Does that help?