Till the End of Time - Edward (Ned) Black - Bog

What if Aliens invaded Earth and humans had forgotten how to fight?
"Till the End of Time" is the fourth book in the Knife Soldiers Chronicles following the adventures of Frank Farrell, a very unwilling time traveler accidentally dragged 600 hundred years intro his future by an experiment gone wrong. He arrived up time at the end of the final world war of Earth that killed over six billion humans worldwide, destroyed most of Earths Civilization, leaving the survivors of Earth population complete pacificists trying to rebuild civilization with the aid of an artificial Intelligence known as the Main computer entity, until the alien attack. Now the AI is working closely with the military assisting in both defeats of the invading army from Andromeda. The Main computer was known as God by the military. Having defeated the aliens known as Delta Mike (DM) and barricading the wormhole used by them Frank is sent on another time travel experiment to prove the arrow of time can move both backward and forward.
The experiment is successful and Frank lands in 1915 where he joins the marines and distinguishes himself in the banana wars, as well as in World War 1. After five years in the past plans for a second invasion and another blackhole are discovered and he is recalled. Frank and fellow marines, Alonzo Blanco, and Alicia Macaldowie explore this new blackhole along with scientists Dr. Sam Lamont, and Dr. Myra Starfold and find themselves involved with strange societies and possibly new threats to Earth, and the human race. Setting the stage for them to prepare to use what they've learned to protect Earth that may be vulnerable to future attacks.