I can't recall the title or author of this novel even though aspects of it remain fairly vivid in my memory. It was about a desperate gamble to "teleport" a military unit lightyears across space behind enemy lines. The signal had to be received by a device within a certain time table or everyone in the transport signal would be dead. The main protagonists were a couple, I think they were married. They were to infiltrate into enemy space, set up the device, and make sure the the army rematerialized.
Then it gets strange as it's discovered the enemy (a once-defeated faction of humanity who rebuilt their military in a remote sector of space) had traded or tricked an alien species into giving them advanaced bio-engineered weapons. The aliens had extreme sexual dimorphism, the females were sentient quadrupeds and expert bio-engineers (their technology specialized in organics to the exclusion of all other topics), the males were barely sentient flying bat things useful only for reproduction.
I read this in the 90s. I believe the book was a hardcover with a typical, non-specific giant space ship on it (the main reason I picked up the book at the library). I found the story enjoyable and would like to reread it and see what else the author wrote.