The Guardians - Book 3 - The Guardians Series, Books 1-3, #4

Earth Defense Forces capture several Tyrax prisoners during the Asteroid Belt Space Battle and learn an awful truth about what the Tyrax are planning next. They are developing a brand new weapon to use against Earth; a weapon so powerful it can destroy whole planets with one or two bombs. The Tyrax are building a large particle accelerator to create an antimatter weapon to use against Earth. The first opponent to build the weapon will win this Galactic Space War between good and evil alien races.
Back on Earth, the world is trying to recover from the damage the Destroyer Weapon Asteroid caused in Greenland and Northern Europe from meteorite fragments. The Tyrax have attempted to destroy Earth and all humans on the planet twice now. It is time for the Latarans, its Alliance Partners and Earth to go on the offensive with new weapons, recapture lost space territories and push the Tyrax back to their dwarf galaxy.
New characters come to life in this book who are part of the newly formed Space Marine Expeditionary Unit training for land assaults on alien planets. A giant struggle ensues to save Òmon's home world called Delton from Tyrax warships. Soon follows a final Victory or Death space battle to end the Galactic Space War once and for all. The destruction caused by antimatter missiles is almost beyond comprehension and will be used as a deterrent to war for generations to come.