I read this great novel about 30 years ago. I don't remember the cover but it was a paperback.
A terrible war is fought between humans and aliens that look like spiders but are larger than humans.
An important point in the book was that only veterans of that war were allowed to vote.
There is also a movie based on the novel, but I was very, very disappointed by it since it was mostly battle scenes and all the societal aspect was almost absent.