Topic 1.6b what is the message for the book of war of worlds

There can be a variety of messages-- typically a book will speak differently to each reader because each reader has different life experiences, and different ideas/morals. 
For me personally:  It had a very huge anti-imperialist theme.  It criticized the British imperialist escapades abroad, and it tried to exhibit that what Martians do has little difference compared to what the British Empire had done.