I'm looking for the title of a novel.
It's about a soldier who returns to Earth after the lunar station he served at was surrendered to the Martians. This was after a long war between the two planets. In New York City, the soldier meets a woman with her daughter who accompany him to his house upstate New York.
Later they are forced to share the house with a Martian unit who use it as sort of a military base.
During the visit of two high ranked officers, they find out that the war was actually started by a shapeshifting race in search of a new home.
I think the author was American and it was written in the 70s or 80s.