same = savagery as mention in the 前一句.
may be said = said = equal to
laying waste = wasting,plundering,robbing by force
held by = controlled
The whole sentence = The action of intentional robbing,killing civilians and destroying a country by force because it could not be controlled by the occupying forces was a savage act done by savages and it should not have happened in a war of a civilized world.(This seems to described the Japs in China)Brilliant!
It's my homework on Canadian Histroy. These words are actually used to summerize the outrage committed in St. Albus America by the confederate raiders(refuge in Canada).
Thank you so much!