Books: The Stars at War
"The Stars at War" is a collection of four space opera novels written by David Weber and Steve White. The novels are set in the "Starfire" boardgame universe, where humans and their alien allies have colonized a handful of planets in a vast and unexplored galaxy. That vastness sets the stage for surprise invasions from two groups of aliens: the fanatical Thebans (the first novel, "Crusade") and the carnivorous Arachnids ("In Death Ground," "The Shiva Option"). It also creates the political tensions that lead to a Terran civil war ("Insurrection").
Weber and White's writing is the military sci-fi equivalent of a Michael Bay movie - there are giant fleets of ships clashing with ever-deadlier technology, big explosions, and broadly-drawn heroes. It's anything but subtle, and if you don't like reading about the point defenses of superdreadnoughts and light cruisers, you're probably not going to like this. That being said, White is a former U.S. Navy officer who served in Vietnam, so the books are also chock full of observations on naval life and fun callbacks to real-world history (the "Great Marianas Turkey Shoot" is referenced by name).