Some of the Honor Harrington books might be just a touch racy for a 12-13 y/o, but would be approriate in a few years. Good reading.
If you have time to do a little recreational reading, you might want to check some of the Honor Harrington books by David Weber yourself. They are I believe intended for an adult reader, but see our discussion about challenging books. Good reading and might turn your daughter towards a career serving aboard CLACs.