Sentence:  The column was placed under the orders of Major Renaud, who pushed up the road; fighting as occasion offered; <WSD>tranquillizing</WSD> the country by the very simple expedient of hanging everybody who showed signs of insubordination ... 
Meaning of the word marked with <WSD> tags:  To make (something or someone) tranquil.<ref>(Thomas Blount), "Glossographia," London: George Sawbridge, 1661: “"Tranquillize" (...) to make quiet, still or calm, to cause tranquility.”[http://name.umdl.umich.edu/A28464.0001.001]</ref>